Starts and idles terrible

I bought it as a winter rat a year and a half ago. Always idled a little rough and stumbled when stomping it up a hill. So just used it around town and took it easy. I really enjoy the truck, it’s nice. 2000 Edie bouer v8 5.4. Now it’s undrivable. Start terrible, sometimes stalls, nearly pulls itself forward the surges and squeals the wheels and then dies.
Ok so I am no mechanic but... I scanned it, misfire #3 and #1, 02 sensor error.
So I pulled all 8 plugs and replaced them (with anti seize)and the coils. #3 plug was destroyed. Started and ran slightly smother, still hunted a bit at idle, ran pretty good and hard, misfire went away, cleared 02 Error and check engine never came back. It was”ok” enough to get around. Now cold started it and worse than ever , stalls, hunts, spitters, nearly pulls itself around.
. I pulled off the egr valve and it’s cruddy but hold a seal, verified it’s not allowing hot gas by by checking air intake manafold with a thermal gun. Looked a lines for a vaccume leak., sprayed carb cleaner around air intake manafold, no sign it suck any into air intake through a leak. I dumped half a can of sea foam in the gas tank, I’m going to change the fuel filter tomorrow but I doubt it’s going to help. Scan tools shows no issues. Any next step ideas?

Did you inspect the inside of the throttle body, and clean it if it is dirty?

I have not inspected it yet, I can pull it off next

cats?

Have not checked the cats, any thoughts on idle air valve?

What about fuel pressure?

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Cteske said:

I have not inspected it yet, I can pull it off next

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I can almost guarantee that you'll need a bit of cleaning inside of that throttle body where the two EGR ports are. Were you in idle with the A/C on, or is it always doing that? My idle fluctuates only when the A/C is running. If it's always idling rough however, then you can dismount the IAC and use IAC cleaner on it. However when you do it, make sure it is absolutely dry before you put it back in.

Also, are you able to read live data? Fuel trim numbers will help out a lot. Perhaps there is a vacuum leak coming from the lower and upper intake that you can't get to. I did a smoke test by using a cigar to the intake via brake booster hose and that's how I found that I had an intake manifold leak.

I bought a vacuum gauge for 15 bucks on amazon. I have had stalling issues with vacuum leaks, usually because i did not put it back on when working on something. I am also happy with my new feul injectors but expensive fix.

I seem to have resolved it, I swapped out the fuel filter with no change. Went to clean mass air flow sensor and throttle body , found a loose hose before the sensor, put my hand near it and it whistled and idle improved. (-: then seated it properly and truck runs like new . Lol. I’m going to run it around town and clean the throttle body I’ve the weekend, but wow what a difference now. Runs better than ever. Thanks everyone for your time