So i bought this engine couple months ago i have had it running from march till now july 14 i have been tinkering and cant get the power i should be getting. its idles great put it in gear and about 1400-2500 rpms i can hear a missfire at 3000 engine grabs hard up to about 5000 then will drop back down to about 4200 and wont go much higher than that. i have checked timing i have 8* atdc and 21* btdc i have checked spark or all cylinders. one thing i am gonna try today is checking spark on all cylinders all the way up to 5000 rpms and see if i lose spark anywere. i have been doing this on the cheap side because i have 4 mercury 200 blocks laying in my yard i know used parts are not the smartes idea. i have changed the trigger and the switch boxes no change strong spark though. i would appreciate any suggestions