Vacuum leaks causing high idle?
 

I have a high idle speed that started out intermittent but is now almost continuous. Cold start idles fine until I touch the throttle while in gear. It will bog slightly and the idle speed will jump to 1500rpm. Normally the problem will go away once it reaches operating temperature. Really acts like a vacuum leak. So far I have checked:
EGR - replaced with a cleaned used valve and cleaned manifold port. Same idle problems.
PCV - all connections seal good with valve plugged
EVAP - unknown but no codes thrown
HVAC - leaks, will not hold vacuum
T-case switch - small leak around plunger(both installed and removed)

I understand the leak in the HVAC being caused by the ATF which probably was caused when ATF entered the system through the vacuum switch. Does the switch begin to leak because of the ATF also? I have not drained fluid from the transfer case yet. I'm planning on replacing the input seal next to prevent this problem if it resolves the issue.

I've also checked the spider/regulator for leaks that could cause a lean condition. Checked good since being replaced 1 year prior. Also replaced fuel filter.

vacuum leak or air entering the intake plenum after the MAF sensor

Regulator leaking would cause a rich condition

I've had little luck tracking down an HVAC diagram online. Pulled the HVAC controls and I'm hoping I can test individual lines to find the leak.
Ordering T-case seal and switch so far.
Any other parts I might need while I'm at it?

is this a first gen? If so,to rule out leaks in the hvac,pull that vacumm line off the back of the manifold (left side) and plug the manifold. Now see if it runs good,if so. you do have a leak somewhere.

It's a '95 with the stupid CPI. I'm starting to think a 305 with TBI would be better.
Why could I rule out leaks on a first gen opposed to anything else?

After tracking I finally found the leak at the short hose feeding the HVAC vacuum in the engine bay. So I replaced that and the transfer case switch again. Now I can draw a vacuum and it pulls down fast and holds pretty good. I also applied some non-hardening silicon to all the connections so they will hold even if the hose is a little loose.
This still did not fix the problem and I found the TPS was at .710v I adjusted it back down to .513v last night so hopefully that fixes it. It was an intermittent problem before and I'm thinking that maybe it's the connector that is the issue. It would explain why the voltage will change. Either a broken wire or a dirty connection. If it happens again I'm going to replace the connector. Spend a few $$ instead of beat my head against a wall with this thing.

I bought this with a salvage title and a blown trans so I'm not sure why I expect much from this thing.

Finally replaced the TPS connector and checked the resistance sweep. Wasn't smooth so I went back to the original TPS and it is A clean sweep. Started it up and it fired right off and idled smoother than ever. I can stab the throttle and RPMs jump quickly. I might actually like to drive this now and not be afraid of the wife driving it.

Problem solved. Thread closed.