I have bought a 94 S15Jimmy AT 4wd V6 4.3 vortec from a guy who said it stalled and then later would idle rough but would stall when he pushed the gas.When I picked it upI could detect gasoline oder under hood, First thing I did at home was check the oil and the gas smell was very strong on the stick and the oil was not right. Sure enough I drained about 3 gallons of gas and oil mixed from the crankcase.The best place for gas get into the crankcase is inside theintake plenum. Inside the plenum I have discovered besides alot gas is that the Nut Kit (that is what GM has named the gas line that feed and return gas inside the intake itself) was leaking.The next thing I discovered was that the spider injector popets (the plastic line that run tospot in the intake just above each cylinder) were melted because the gas had caught on fire inside the plenumI will post pics as soon asI get a chance I am going flush the gas from the lube system. Then pull the plugs and lube the tops of each cylinder because the gas will have washed all lubeaway. Then I willreplace the nut kit and spider injectorwith a good one I have on handif the engine turns out to not damaged by the ordeal then I will get new nut kit and injector,otherwise I will needa anotherengine. I was not surprised by this! I have seen and heard of so many cases like this! In my opinon if you are running rough orgetting worse that normal milege and a tune up does cure the problem you need to see what is going on inside your intake. The upper plenum comes off and on very easy in less than an hour for each. The gasket runs about $15 if you need more than thatThe Kit to replace everythingstart at a little over $300andif it needed the results are worth 5 times thatThis enginemight beruined and that is a shame because if he had opened the intake it firstdied that likely would not be the case. And Please if you can smell gas under the hood and cannot find the source,check you spider injector. The guy that sold me this truck did not get much for it, but he was lucky to even have at truck to sell

 

Not for nothing, but I'm guessing that the guy who sold you the truck already got the news about what work ($$) was needed. When you have that much gas in your oil, you know your fuel lines are leaking in your plenum. Not many mechanics are going to just replace the nut kit only anyway, even if nothing was melted.