2001 5.4 2v low power...cats?

Hi folks, looking for some help on how to diagnose my issue, quick breakdown:

I bought a 2001 Expedition with over 200,000 miles, its a California car with full emissions. The owner said the head gasket was bad. When I checked the oil and water no signs of mixing but the coolant was getting pressurized. The truck started and ran and idled fine but seemed to be misfiring bad. Cylinder #1 was dead per the codes it was throwing. After some searching around I figured it more than likely was the intake manifold.

I changed the Intake manifold, spark plugs, new coil on #1 and replaced all the boots on the rest of the coils. Did the passenger side valve cover gasket cause it was leaking, new air filter, new fuel filter, new PCV valve and tube, and cleaned the filthy throttle body.

Fired her up and no more missing in the motor but it felt like I wasn't getting close to full power, lag in acceleration like I was hauling a heavy load.

Based on the dead cylinder and unsure of how long the previous owner ran it like that with unburnt fuel dumping into the exhaust I'm dreading the CARB cats.

The truck sat for over 2 years... so I put fresh gas in and when it was less than a 1/4 tank I ran some CATACLEAN through it and it did help smooth it out on throttle response, but still much to be desired.

I took it up to Tahoe and the mountain climbs were painfully slow but with some time I could get it to do highway speeds on the flats.

SO MY QUESTION IS:

I got under the truck when it was cold started and could smell exhaust on the passenger side, same bank as the dead cylinder. Could a small exhaust leak on the manifold be enough to cause this?

I purchased new exhaust manifolds when I bought it cause I saw its a known issue and the truck has plenty of miles.

If not, what's the best way to test my Cats to be sure they are either good or bad?

Thanks!

Forgot to mention:

NO Check Engine light or pending codes
No egg smell... ever so slight sound of debris when I hit the cat on the passenger side

Usually they do an exhaust backpressure test. Check you tube. Also do a cylinder compression test and fuel pressure test.

After a long drive a clogged cat could glow red if it's really bad. You can use a laser thermometer to check the temps. If you have 4 cats, verify that both front cats are about the same temperature after driving for a while. Do this with the rears as well. If one is much hotter than the corresponding one on the other side then it is clogged. You could also pull the O2 sensors, go for a quick drive and see if you have more power. This allows exhaust to escape through the holes for the O2 sensors, negating a clogged cat.

So Update:

I changed the passenger side Catalytic Converter and both 02 sensors with Denso units, high quality. Runs much better and has more power but still has a ever so slight hesitation. Not the funniest job without a lift.

today I was going through some fuel tests. I have 33ish psi with key on engine off.... and 33ish psi at idle. Fuel pressure goes upto 40 when I take the vacuum line off the FPR on the drive side fuel rail. No smell of fuel in that vacuum line. FPR seems to be passing basic testing.

I ran some real time data on my scanner and I have some questions:

I have 4.69% on Long term fuel trim 1
I have 0.00% on long term fuel trim 2

I have -.46% on short term fuel trim 1
I have -1.82% on short term fuel trim 2

My Baro pressure is 157.36hz, seems good to me I’m at about 200 feet above sea level. So I’m assuming MAF is functioning ok.

TP sensor was at .90 V at idle

Air intake temp sensor 2.53 V at idle

MAF was .87 V at idle & 5.53 G/S

heated exhaust gas oxygen sensor bank 1 sensor 2 read .20 V at idle, Bank 2 sensor 2 read .69 V at same idle

fuel tank pressure was -2.39 Kpa

photos to follow once I get them uploaded to a photo server.

The difference between fuel bank numbers and 02 values has me wondering if I have an issue with fuel delivery or a unmetered air/vacuum leak.

The fuel pressure held on my test gauge at 30 plus psi for well over a half hour, it did seem to go up slightly when I turned the ignition off and let it sit, don’t know if that’s anything. So I’m doubting a leaking injector.

Is that idle fuel pressure good enough or is it supposed to be higher?

My exhaust manifolds are rusty as all hell and will get replaced in the next month or two, would this slight exhaust leak be enough? I can hear some exhaust at start up but nothing too crazy, it does get quieter once the metal expands a bit.

Any help with trouble shooting is much appreciated.

im also wondering if 240,000 miles have taken their toll and this is the power band I have to work with until I swap a fresh motor in?! No I haven’t done a compression test yet lol... been avoiding that but may need to do em I guess damn it

YouTube video of me showing fuel pressure and reaction to quick throttle revs

so I have a slight leak at the connection between the bank 1 exhaust manifold and downpipe, going to try to get that junction to seal and see what happens. Also going to test the TPS and rule that out, going to build a smoke test machine out of PVC pipe with a tiki lantern wick and baby oil to rule out any other vacuum leaks, I did the PVC elbow and put hose clamps on the throttle body connections to seal them prior when I did the new intake manifold. I'll keep updating for searching purposes.

I used a combustion gas tester on the coolant and initially it failed and I shit myself, thought head gasket did in fact fail, but I flushed the system and it passed, I think there was still fuel and combustion gasses in the coolant from when the coolant passage failed in the intake so I hope I dodged a bullet there.

You shouldn't see more than 3-4 psi in the coolant reservoir. If you see any soot or smell exhaust in the reservoir, or you're blowing any coolant out as overflow, then you still have a head gasket leak. It's very common on any of these motors over 200k+ miles on the clock. Really the heads aren't that big a deal, as long as you get the heater hoses off and out of the way. When I did mine I sent the heads out to get rebuilt anyway with new springs, seals, rocker arms...

Can you set up your fuel pressure gauge so you can see it through the windshield with the hood closed ? Go for a test drive and see what your fuel pressure is doing under load? 30 psi is on the low side of the specs. Something between 40-50 would be better. If you see the pressure dropping below 30 under load I'd definitely go for a new fuel pump. Bosch is a good brand if you don't want to splurge for a Motorcraft.