Possible misfire

[Franks 2003 HD]

I just purchased a 2003 F-150 H-D with 62,000 miles. The truck runs fine as long as I don't go past about 2,500 RPM. If I pass 2,500 the truck seems to have a misfire and doesn't make boost. I was told to reset the ECM but I'm not sure how to do this. I disconnected the battery overnight and that did not fix the problem. Any help is appreciated.

 

[flip_86]

I had a similar problem with my 02 , no check engine lights, ran fine when just cruising around but anytime i really got on the throttle it had a terrible misfire, ended up being spark plugs, the electrodes were wore down bad and drastically increased the spark plug gap

 

[Ladmarines]

Same here. almost like the engine was shuttering or something. pulled all the plugs they were bad. one had backed out some and has a leak

 

[SonicHD]

Start with plugs, and if that doesn't solve the problem, look into your coils next. Could be just one. If you do a search, you should find a how to on how to test them.