1995 GMC Jimmy Bad idle

I also suspect a vaccum leak or a fuel pump problem. Is there a way to test the spider injector? I had the intake open today to find very small puddles of fuel. It was also filthy. Keep in mind it is 16 years old. Thanks for the info!

I had the truck hooked up to a diagnostic machine only to tell me the MAP sensor was reading low. I replaced the MAP sensor. It helped a bit, but did not solve the problem. How can I test the fuel pressure? Can I spray the vacuum tubes and around the intake with WD40 to check for a vacuum leak? I appreciate your help.

The fuel pressure regulator is a reasonable cause for my problem. I've since replaced the MAP sensor and the TP sensor. They made minor improvement. She still idles horribly. FPR is a fairly cheap part (Under $60).

I really need to have a fuel pressure and vacuum tests done. I will probably end up taking it to a shop for those.

Any other suggestions are appreciated! Thanks again.

I swapped the EGR valve already, but it came from a junkyard. I also replaced the gasket. Thanks for your help! Any more ideas? I'm about to put some more cash into her this month. I have a FPR on the way and debating on just buying the injector. If that doesn't fix it, it has to be the fuel pump or a vacuum leak. Almost every sensor is new. The only ones I haven't changed out are the oxygen sensors, and the ambient air temp sensor (which is vacuum related as I understand at this point). I'll definitely keep you posted. Thanks again!

Put a new injector in, cleared up a lot of the high idling, better fuel economy and more power restored. It is still spiking DOWN now and sometimes stalling around 500RPM. Still have a slight misfire.

Had the same problem with my 95 Jimmy. Turned out to be loose bolts on the lower intake manifold causing a vacuum leak. This actually happened twice. I found it the first time when replacing the gaskets. The bolts were finger loose but I changed the gaskets anyway. About a year later I got the same symptoms back. I located the leak by spraying around the base of the lower. Upon pulling the upper I found the bolts loose again. The specs on some sites say to do a final torque of 14 ft lbs. I found one site that said to do a final torque of 30 ft lbs. Which makes more sense seeing that they are 3/8 bolts. I did the 30 with some thread sealer on the bolts. Runs like new again. Hope this helps.