91 gmc sierra

[pattdr]

I have a 91 sierra 4x4 that started running really bad all of a sudden. I thought it was the fuel filter and changed it out, but that did not help. Plugs are good. It will run great for a while and then starts acting like it wants to die and the exhaust smeels really strong. It will act up for a while and then run good for a while. It has a 350 engine. I have ran the tank empty and put fresh gas in and also added additives to the fuel to clean system. It has a new engine with only about 2500 miles on it. Any suggestions.

[maxwedge]

Welcome to AF, many things can cause this, look at the fuel pressure, must be 10-13 psi.

[juggie#1]

sound like the MAP sensor is Bad, did u change the fuel filter, IT can also be the module going bad.

[2000CAYukon]

What temp is the engine coolant temp sensor reporting to the ECM? If this is wrong, it can run rich.

//2000CAYukon