Just got back from a 1,000+ mile road trip for a funeral. About 150 miles into the trip the "service engine soon" (SES) light came on, felt like the car was mis-firing but due to time constraints couldn't stop to fix it. After arriving at destination took it to mechanic to verify and indeed it was a misfire. Changed plugs and wires and cleared error code. Engine still shook a little but no SES light. Headed home, about 250 miles in SES light came on again. Upon getting home checked OBD code still showing misfire in cylinder #1. Also just this once car had trouble starting and needed a jump, also wife (her car) tells me "oh yeah, had trouble starting a few weeks ago and when I had the oil changed they said the battery was showing low." Any other ideas what could be causing misfire? I thought maybe coil but read that I should get misfires on both cylinders that are attached to that coil also tested with multimeter and didn't show any problems. Also as far as I can see battery tests fine with multimeter as well. Other thought is it may be fuel injector. Thanks for any help.
99 Grand Prix 3.8L V6
143,000 miles
