Last week my car was running great. I had just put new plugs in it a few weeks earlier. Anyway, I went to Sam's and had new tires put on. When I picked up the car it was missing badly. I asked the tire tech If he noticed it and he said yes. First I looked under the car to see if he had jacked the car up wrong and mashed/bent/shorted something but everything looked ok. I checked the plug wires and each plug was firing. I checked the cap and rotor and they looked bad so I replaced them. The car now misses at an idle and when your driving it seems to quit missing every once and awhile....even running normal for a block or two. I put some injector cleaner in the gas but that didn't seem to help. I don't know what else to check. Any ideas?
Thanks in advance!