What is this oval shaped black canister with one vacuum line under the passenger front fender. I think the vapor canister is on the driver side under the ECM or PCM whichever it it

tested the TPS with the meter like in the how to you linked. It tested out fine. went up and down very smooth and acurratly. I could control the numbers displayed by opening or closing the throttle.

couldn't find any vacuum leaks anywhere. at this point im leaning towards the IAC valve. its cheap enough I may just through one at it. 170,000 mile on the car. im sure it cant hurt

i agree. some cars have vacuum boosters or cans for evening out the signal or adding vacuum in times of low signal. most cars have a labeled diagram on the rad support

Whelp I replaced the IAC and it still runs the same. I'm at a loss here. It'* gotta be a vacuum leak somewhere when the lines get hot they're prolly creating a leak. Bit whiles it'* surging at idle I can pull any vacuum line off and it idles normal. I pulled the fuel pressure regulator line off to be specific

there is a boot that is a common failure on these, on the throttle body one vacuum line goes to the reg the other goes to the evap purge solenoid. the whole line is suspect really. anywhere that has rubber. my boot was dry rotted not split or anything and i had the same issues the only way you could tell the problem is taking it off and looking at the boot while flexing it and it looks like 30 yr old tires. so i just replaced it all. you can get vacuum tube and tees and do it that way or go to the dealer and try your luck. thats what i did and i got the guy to let me look at the screen and it looked like the one part number just pointed at one line and labeled vacuum tube or something like that, came with the plastic tubes and that boot, then i replaced the metal line from the evap solenoid to the canister with generic vacuum tube from the parts store. the gm stuff was about 30 bucks maybe 5 yrs ago

I pulled the map sensor off and found the PVC valve o ring hanging half way out. Could this be a cause? It'* a positive pressure though not a vaccuum

the map seals the hole if there was no air leak there probably not

The map sensor is just sitting in top kind of rattling around loose. It looks like it should fit tight but it doesn't. Maybe I broke it when I installed it

shouldnt be loose there should be like a ribbed rubber deal to seal the hole on it

Yeah the little orange rubber deal that goes over the sensor slipped off down in there so I removed it with an o ring pick , cleaned it up and re installed it. Good to go now I think it fixed my problem . Haven't got it to act up yet since . Thanks for all the help