I cannot figure out what is going on with this truck. It has a 4.3L engine with "Z" VIN code. I replaced the plugs, fuel filter, distributor cap and rotor, MAP sensor, and IAC valve. None of these things has helped. The TPS seems to be working correctly as I tested it with a volt meter. I replaced the MAP sensor because it was receiving 5 volts but the signal wire showed a voltage of 1.4 volts and did not change with suction. The IAC valve was stuck so I replaced it. The EGR valve tested correctly and wasn't replaced.
When I start the truck(starts easily) it will idle at around 1000-1100 RPM for a about 30 seconds and then drops to about 600 and then to 500 and then stalls. It will staying running if the accelerator is pressed but it is weak during acceleration.
Any help would be appreciated.
have the same problem?
Tuesday, May 7th, 2013 AT 5:23 PM