if it runs fine/strong otherwise then i think you can rule out timing or fuel.

is there a vacuum test port anywhere on these? that might be interesting to see... would give you some indication as to what the IAC was doing.

im guessing IAC issue of some sort though...

This is not a vacuum issue. a 48 is a pretty strong indicator your IAC is going, not sure what more you need.
As for cleaning the t/body, remove the hose, open the throttle plate with your left hand, spray with car cleaner, use an old tooth bunch to scrub out all the old build u, wipe out the excess with a towel and your done. Your engine will be flooded so turn and hold the key till it starts.

You suggest just replacing it at this point?

Best resource?

Took a video of fuel pressure, even though it was only slightly doing this it was still the same symptoms. It seems worse when I get up to higher speeds for long distances then come to a stop.


1995 Discovery fuel pressure - YouTube

You asked about cleaning the MAF.Do it withenginecold.Removethemaf assy from the inlet hoses, pull the front black plastic ring off, remove wire mesh and sit aside.

Spray the MAF cleaner spray in short burst into the little port suspended in the center throat. Invert over paper towel and repeat until it runs clear. Allow to air dry, put it all back together and try it out.

Leave the MAF alone, no since messing with anything that is not causing your problem.

There's a GM IAC which can be used as a substitute. Autozone carries p/n AC102.

My buddy's RRC would throw an IACV code any time it died or almost died, even after replacing it with a new part.

That is because in many cases, you must reprogram the new IAC to work properly for that specific engine.

It would throw that code until he fixed whatever problem was causing it to die, in his case it was an ignition amp. I think if the computer tells the iac to idle up, and it doesn't happen, for whatever reason, you'll get that code.

Well. I am now getting a 02 code which will not clear with the usual battery trick. I read you have to unplug the ECM to clear it, probably a good idea to check out my ECM anyway.