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!

You probably have a plug wire end bad. Very common especially after having replaced the plugs.

This is very easy to see with an ignition scope. Since plugs wires seem to be an acceptable throw away, I might suggest replacing all four. They will be less than paying some one like me to figure which one. Of course it could be something else, that's why we make the big bucks (bg).

The plug wire ends are all that ever go wrong with the plug wires and are easy to replace with a little technique. Here is my technique: first slice the rubber boot at the top of the plug wire end (look at your new end to see what's what) from the metal to the wire. Under it you will see white porcelain. Place a rag around this and squeeze it at the top with a pair of pliers till it breaks. Break it away (don't cut yourself the pieces are sharp) untill you can see the metal fitting made onto the end of the wire. Grab the metal with your pliers and unscrew it from the plug wire end. If you don't do this and try to unscrew it by grasping the wire the wire will almost always tear from the fitting and then you have a problem (fixable but thats another story).

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician