I have a 1999 5.7L Vortec Tahoe that has the #4 spark plug that keeps misfiring. I had it tune-up at around 150,000 and then the first time it misfired was at 171,410 miles, 2nd time at 189,073 miles, and a 3rd time at 195,600 miles. Each time the misfiring occurred, the #4 plug was replaced. I don't know if this may have anything to do with it, but for years, every 700-1,000 miles or so, I have to fill the overflow antifreeze to the cold line. Head gasket? Intake gasket? Anyone ever had this problem?

Another issue is the driver side window. Intermittently, it won't open. It always goes up, but sometimes won't open, and out of the blue, it'll work again. The window switch was replaced, but it did not resolve the problem.

 

I had the same issue on my 99 Suburban. It turned out to be one of the female bayonet plus that go on the motor. I just squeezed them tighter and put them back on. That was a long time age and I can't remember if I pulled the door panel off or if I was able too pull them up with the switch panel off. You can reach them through switch panel if your arm is skinny enough, pull them off the motor, tighten them, and put them back on.

 

Thank you, Larry, I will try that!