I need help diagnosing engine problems. Going broke trying to figure it out!!

ashimusashimus Member Posts: 1
edited June 2015 in GMC
I have a 1999 GMC Jimmy SLE with a 4.3L V6 and 300,000 miles. Three days ago I put a pint of Seafoam in the gas and a cup in the crankcase in hopes of getting better performance. I ran it for about 30 minutes and then it sat for a day. When I went to drive it yesterday, it fired up well and initially drove fine. However, it later acted as if it weren't getting enough fuel and stalled out on me. Today I installed the spider injector assembly and it fired up right away but blew white smoke out from the tailpipe. It later quit blowing smoke but stalled out on me again. When I took the breather off of it, I noticed a lot of condensation in the throttle body.

In the past few months I have had a lot of sluggishness and sputtering in the engine with very little power. In the past nine months I have replaced the plugs and wires, the fuel pump and fuel filter, the PCV and EGR valves, the air filter, and today the spider injector assembly and fuel filter again. I also had milky oil on the dipstick which I assume is from the Seafoam, and I am going to change the oil tomorrow. That is a first, so I am sure it is from the Seafoam.

I need help diagnosing this problem. I am going broke trying to fix this fuel/sluggishness problem. Please help!!

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