sometimes in the mornings especially if it is cool or damp, the truck starts right up, but as soon as you give it gas it dies. let in run at idle for a couple minutes shut it off and restart, usually runs great all day long. sometimes while driving it will lose power and won't accelerate, have to put in neutral, shut off and restart. yesterday after driving about 20mi on the highway it would die everytime I took my foot off the gas at a stoplight it would die. I have changed the TPS & MAFS. the check engine light is back on and reads TPS & MAF sensor along with a lean code. sometimes it will go days without any problems. the exhaust does smell funny after it has been stalling. nobody seems to be able to figure this out

 

Something to check, look carefully for any corrosion at the plugs that plug onto the PCM. They need to be removed to check them.
Also , do you know if the windshield has ever been replaced and some even leaked right from the factory. Water intrusion from a leaking windshield caused many problems with the GEM module that were difficult to explain.