Engine starts and idols good. As soon as the RPMs are increased, engine starts to break up, shake, backfire via exhaust. Port side bank plugs and head very cool as if not firing properly. Compression good in all 6 cyl. Gas seems good, even tested using portable 6gal tank with fresh gas. Plugs all seem to be getting spark, just not sure if in time. Replaced CDI unit with known good, still same problem. Any suggestions?? thanks
