I have a 1988 Nissan P/U XE 4WD with a z24i engine. Under accerlation or under no load at all it misses, hesatates, or bucks whatever you want to call it at 2750 RPMs everytime. I have a code 51 on my ECU but the manual says it is for v6 engine only. I have been told that it may be the ignitors or ignition control modules for the coils but is there a way to check them before paying out a $100 dollars each? I have fire on both coils it is just seams like there is a rev limiter kicking in at 2750 RPMs. Please help if anyone knows what the problem maybe.