Runnability issue hardest i ever had to diagnose

so as many know i have done quite a bit of working with some idle issues ant what not. i am kind of stuck atm. Smooth idle ( though at what rpm it idles can change from day to day but usually in spec. i seem to have lost top end RPM and i swear the new iac valve isn't operating fast enough or something similar. lost quite a bit of upper end power and acceleration. gas mileage has dropped a good amount and if i don't slowly back off the peddle it dies out. starts right back up tho. new iac, egr , plugs , wires and air filter. coil and icm are less than a year old. wondering if clogged exhaust would do that or other ideas . oddest part is no codes at all.

Sounds like you might have an Intake Leak or something of that nature. Have you inspected around the LIM and all the Vacuum hoses for leaks?

I have the best I can with out a smoke machine. But if I just pull my foot of the peddle it drops off if I notice I can catch it by barely pressing the gas . Count to 2 for a stabilize then can take my foot off.

Can you hear any "odd" hissing from the engine compartment when it's running? Is it different hot or cold?

One good little trick is to buy a can of Carb cleaner and spray around the LIM and vacuum lines while it's running. A bad enough air leak will suck in the cleaner and momentarily cause the idle to change on its own. If you happen to find a spot that causes this, and can duplicate it, chances are that's where the problem is.

I assume the SES light isn't on?

Nope no SER light, really wish it was on even tho the obd 1.5 is a p.i.t.a.

Sure sounds like a vacuum line is disconnected somewhere. Check them all!

Do you have to add coolant on a regular basis?

Almost never since I had to to replace the bypass elbows

Can you put a vacuum gauge on it?  I have a combination vacuum/boost gauge in my car, and fully warmed up, my engine will pull 20" in Park.

Have to rent one from work today I will let you know tomorrow

Weird tho. Never had this issue with out secondary issues with a vacuum leak. Not arguing just observation.

Try disconnecting the MAF sensor. Idle will probably stumble a bit then smooth out. If the MAF is totally bad, you'll have all kinds of weird issues kind of like you are describing.

With the MAF disconnected, you should get an SES light right away, but take it for a slow drive. If the drive is better, it's very possible your MAF sensor is no good. Don't do any performance driving with the MAF sensor disconnected.

Do you have an aftermarket air filter or a 'standard' paper filter?

Standard, I'll give that a try

Standard, I'll give that a try

Unplugged the maf. Engine went rough as hell. Couldn't even get out of the driveway. Would a tps glitch cause the die on release of accelerator? If it has enough rpm it can catch itself like maybe the computer is trying to catch it

On a side note I think my check engine light might be burnt out and none of the local auto parts places have the cable to check obd 1.5. Really don't have the cash for a short diagnostiv

Well just tried the tap test on the maf, no difference

Okay sounds like MAF probably isn't your issue. Keep looking!

Triple check your vacuum lines, the nylon tubing can split, the rubber ends can crack causing leaks that are hard to find.

Kk I'll get back as I know more

I am wondering if you have the proper battery installed in the car. If the idle is not operating properly (cold around 1100 warm around 700 I think) you have a sensor issue and that can be simply from having an inadequate or worn out battery. Riv will crank on very little power but it won't run right without a battery having at least 450 CCA as measured while installed no kidding. It's important to have a factory spec battery installed.

Albert

Currently running the recommended from my work with 850 cca 1000ca

The saga continues. Tried a maf. Didnt fix anything and actually developed what sounds like a back fire on fast release from upper rpm. Which got me thinking, last time I had a vehicle that had a similer problem it had a partially clogged exhaust. Milage has been crap does seem to be minus power at higher rpm like it is only using half the throttle.Not to mention the wife remembers a pop we heard one night before ilost my serp belt last and me commenting that my cars tone seemed wrong.i remembered saying it after she mentioned it. So I wonder partially clogged cat? Opinions welcome.looked again under earlier and it looks factory all the way back.270k miles.

Clogged cat is certainly a possibility. Does it sound 'wheezy' when you step on it?

A bit yeah.

Tone deeped when it changed as well

If I pull the air cleaner it sounds fine at idle move the throttle and it sounds like its almost pushing air out than in, tho it is taking it in.been wondering about that for a bit as it was a new sound. Didnt ever here anything like it on any of my old hot rods carb or fi