1999 Expy running rough

[Anitomical]

So I figured out why it was suckin up quite a bit of gas. First the EGR vacuum solenoid had a wire corroded off so I fixed that, but it was still running a tiny bit rough and sucking down some gas still. And I get that it's a hefty old girl but to me it still seems a little much, but hey thats the life of owning one of these things. After I figured that out I took it to a shop to see why it was still running a little rough and they told me it had a misfire, so I changed out all of the coils and spark plugs (the plugs and coils I put in it were supplied by the shop and the spark plugs were a NGK V-Powered). Got them changed and it seemed like it still was missing a cylinder some but oh my lord did it have some power now, and it would actually rev up a lot better and just all around had more steam. But after putting about a hundred miles on it, everytime it got up to temp and idled it would be like really rough. Seemed like it was missing on more than one cylinder at times and at one point it about stalled, it dropped down past 500 rpm and about shut off on me. It also seemed to lose a bit of power too. And the check engine light has been on since I could remember, so I checked the codes the one day and they were all for the O2 sensors (P0135, P0136, P1131, and P1151). So I figured since the light has always been on that all 4 were probably bad, so I check it again the next day... the codes are P0135, P1131, and P1151, so I was confused because what happened to the one O2 sensor? Then again after a week, P0135, P1151... the O2 sensors keep coming back around?? And today I checked and it was just the P0135 code? I've read some forums about a vacuum leak which I will check for but I don't know how I can check to see if they're leaking or not.

Engine: Triton 5.4L 2V
Sub-model: XLT
Odometer: 176715

 

[Anitomical]

Also for anyone who was wondering, the spark plugs were NGK TR55’s.

 

[Anitomical]

Update: I was looking in the engine bay to see if there would be anything to catch my eye, and low and behold there was. The metal line for the PCV looked somewhat kinked, so I looked at the rubber lines right on the pcv and they were completely just destroyed. I dont know if that's what would cause the issue but it's a start.

 

[Hamfisted]

A smoke test machine would come in real handy for your issues.

Mechanics Smoke Test Machine on Amazon







.

 

[Anitomical]

A smoke test machine would come in real handy for your issues.

Mechanics Smoke Test Machine on Amazon







.

True just $100 for a small smoke machine is just wow, ill see if i can build my own a check. I only have two lines im concerned might have a vacuum leak, ill take a picture of the ones later on because im not to sure what they’re for and i need to know which ones to order. Anyways it’s kinda hard to see how messed up the rubber line is in these but this is what the PCV lines look like.