Need help with 89 GMC Sierra K1500 350 tbi
 

Calling the TBI experts! Truck will start and die after about 2 seconds. Fresh non ethanol fuel, new fuel pump, new fuel filter, new regulator, new injector screens, new distributor cap, new rotor, new plugs,and new battery. Truck had been sitting for a while so I drained the tank too. If I pull the vac line of of the map sensor the truck will fire, idle rich, and can be revved to part throttle before falling flat to stall. If I put the vac line back on the map sensor it will stumble and die. If I pull the harness from the map sensor and leave the vac line attached it will fire and idle. It leaves me to believe the map sensor is bad. I took the egr valve out of play to narrow down possibility. If I unplug the coolant temp sensor it will idle like crap. No vac leaks, strong spark, good injector spray. With the vac lines unplugged it will actually idle higher. I'm down to map, tps, or idle air valve. Really drives me crazy. I've had the truck for a long time and never had this issue.