Newbei here.

I have a 1996 Jimmy (different sheet metal) that starts/fires-up fine when cold. You barely touch the key.

After it warms up it's a different story. You have to crank it for several seconds to get it started.

I have replaced, both coolant sensors, AIT sensor, MAF, and TPS sensors. The feul pressure reads around 60 psi both cold and hot when the key is turned on, and drops very slowly after the key is turned off.

Any help please.

 

Sounds like you could have a fuel leak under the plenum that is causing a rich condition on hot starts. Does it start any easier if you hold the throttle to the floor?

 

I will give that a try. I had one suggestion form another site that mentioned that the fuel presuure regulator and some of the tubing could be leaking. That would give the rich condition that you are talking about.

I just had to pay $700 to replace the intake manifold gasket for a coolant leak. The plemium is black and sets onto of that right? Throttle plate and housing is on top?

 

On the SCFI engine, there really isn't any additional things that could be causing a fuel leak like there is on the older CPI engines (95 and earlier), but the FPR could leak or an o-ring on one of the injectors into the main injector pack housing.

You are correct on the plenum. It is the black plastic piece that the throttle body mounts to.