2002 Ford F-150 Triton 4.6L 152,000 miles...had engine looked at after engine light came on. Dealership said I needed new spark plugs. Replaced and was runing better. Dealer ship put some injector cleaner in too. Drove truck awhile and it started runing rough again but not as bad as the first time. Any Suggestions??

 

Did they replace the COPs?

 

I didn't know what COP's are but I didn't pay for anything else except plugs.

 

COPs are coil over plugs [the coils over every plug]. I can't believe they didn't try to sell those while they were changing the plugs

 

Is your engine light on? sound like they only did half the job of tuning it up.

 

After I left the dearlership, the light came back on after 50 +/- miles.

 

[U]GOOD NEWS PROBLEM SOLVED The #3 plug was so bad that it caused the injector to clog. After putting injector cleaner in a couple tanks of gas...the engine started running smooth and the engine light went off.