'90 Dak Won't Start when Engine is Warm

My '90 Dak (144k, 3.9L, 5sp) will not start once the engine is warm. Starts on first crank in the morning, or when the block has cooled. If I run it for 15-30 mins and shut it off, it will not start. The motor will crank but will not catch. If I let it sit for 20-30 mins, it will fire right up again.

Any thougts? This behavior just started and may be related to a bad tank of gas. I had a mech pull and dry the tank, blow out the fuel line and injectors and replaced the fuel filter. Still runs rough.

Truck had a new fuel pump installed in 03/2003.

Thanks!!

Here's some additional info - With the truck warmed up but not starting, I definitely have spark at the coil and I definitely have fuel coming into the throttle body. I do hear some clicking when I first turn the key and the gas pedal depresses slightly (by itself)

It's also give an code 13 - MAP sensor or vacuum line may not be working.

Truck definitely runs worse the longer it runs. First 4-5 minutes, it runs great. After 10 minutes its missing, chugging, backfiring and a real pain in the @ss to drive. After 15-20 mins, it will barely idle when still and will often croak if I touch the gas....then I have to pop the hood and let it cool for 20+ minutes, then it will start back up and run will till it heats up again.

Would a bad MAP sensor cause this behavior?

Thanks!

I swapped out the MAP sensor and it made absolutely no difference whatsoever. Going to try to return the $60 piece of plastic tomorrow morning.

What else guys?

Severe timing issue?

Failed plug?

Again, it runs great for 5 minutes then quickly declines into sputtering, backfiring nightmare.

Overheating transmission?

I'm totally grasping at straws.

PROBLEM RESOLVED

I changed the coil, distributor, rotor, plugs and wires and it runs like new. I think the coil was the culprit for as soon as I swapped it, the truck fired right up even though the block was still warm. Now runs smooth at any speed. No backfires, no misses, no hesitation.

I bet the EGR is original to the truck and the o2 sensor probably is too, but I don't want to go borrowing trouble by replacing them.