hello all. i have been searching around the net in hopes for an anwser but i cannot find one so im coming to the forums. my 1984 f250 came factory with a 4.9 liter six. the previous owner took that motor out and installed a 351windsor in its place. i removed that due to the fact it had no power and put in a newly rebuilt by me 302, so i know everything in the motor was done proper. however i put the motor in and it still runs like crap. there is a certain hill on the highway and im lucky to get 50 mph with my foot burried in the carburetor, just like with the 351, loaded kenworths blow by me
. is there a chance that the guy i bought the truck from installed the 4.9 liter six flywheel on the v-8? would a incorrect flywheel cause a motor to run that bad? there is a notice able vibration when you are going down the road when you are not on the gas at low rpm the whole truck will lerch forward and almost like you were blurping the throttle. i have tried adjusting the carb and timing and everything. i have timing set to 8 degrees inital and carb tuned so it will run as smooth as possible. im really hung up on this one. ive been told a 4.9 six will bolt up to it but i do not know what the performance loss could be. long question short, will a incorrect flywheel cause my motor to be a sick dog???