it might be the cam i hear it frome the exhast but i never see the rpms drop more then a 50-100.I am running it with procharger atm because i havent got the motor broke in yet.Now that you say that it prolly is the cam.

 

If you have a misfire on an obd2 car (post 96), there should be at least a misfire code which will tell you which cylinder (or if more than 1 several codes) is misfiring. There could be other codes too. DTC's are mans best friend when it comes to engine diagnostics!
So....... it sounds like the misfire is caused from a component which was transfered to the new engine. Do you have any exhaust or intake air/vacuum leaks ? Evaporative cannister or purge flow circuit could be faulty. Without codes though it's like a stab in the dark, so many things can cause a misfire. Did you transfer any engine sensors to the new engine ?

Also Bosch plugs don't seem to give good results on some Ford engines, especially the platinums. The centre electrode burns out too easily.

ATB Steve.

 

Ahh.... if you have a high lift cam that could make a lumpy idle, (not really a misfire but sounds similar). Would not throw a misfire code either.

 

not throwing any codes. no leaks of any kind.It only sounds like a miss at idle.when running it nothing just pure strong power.

 

just cam lope