I have a '99 camaro with the 3.8 V6 series II engine it has 183,000 miles and was running fine up until last week. A bit of background the car has had the fuel pump,sending unit,pressure regulator,alternator and water pump replaced in the last two months.

The car began idling rough and running really rough and misfiring bad.,I had autozone scan it and they said it was misfiring by the codes they got. a few days ago,last night it stalled and wouldn't re start until I jumped it at which time it turned over and ran really bad like it was gonna die. When we pulled the cables off the battery my voltage meter in my dash just dropped to nothing like the car had no voltage but all the lights and radio still worked.

This morning I put a new battery in it and it started up and ran Luke a top idled glass smooth I drove if 20 minutes to work and it started misfiring again bit not as bad as before,any idea what's causing this problem? Could it be my spark plugs and or wires?

 

I have had a very similar problem with my 2000 silverado 5.3L vortex with 176,000 miles on it. The fuel pump, sending unit, fuel filter and knock sensors were recently replaced. I took it to a GM dealership: misfiring, rough idle and stalling. After the ran the codes they could not figure it out, but they did tell me that the fuel in the tank(took a sample) had a foul odor. They suggested using top tier fuels: Shell, Mobil, Chevron, Sunoco. Stay away from the lesser brands, especially the mom&pop gas stations, you just don't know how long that gas has been sitting in the tanks. After followimg that advice the problem has gotten better, although not completely. One other thing to consider is ETHANOL blends are known to break down older rubber and plastic fuel system components.