As some of you may know by my recent post I’ve been working on replacing the engine in big green. 99 K2500 Suburban 7.4 It was rebuilt at an engine shop they punched it out 40 over and put a comp cam shaft in it I will post the card on it so I got it installed and started it up today and it’s not running very well almost like the timings off a tooth. I set up a distributor to top dead center. It rev,s up to about 1500 drops down to 500 and Keeps going up-and-down up-and-down until it shuts off. I will post a video of it. Could it be too much cam for the ECU or could it be the timing off just a tooth or two?