By the way; the lake or sea water temp has nothing to do with the engine performance.

FWIW my 454 mag looses about the same rpms if silent choice is set to silent (exhaust through the prop)--shooting it out the back lets it rev out. I agree that fuel pressure is the most likely issue, but if you have through-prop exhaust or mufflers make sure they aren't restricted.

Start with the basics,I agree.

thanks alot, sounds like sound advice and will proceed accordingly.

Lake/Sea Temp is not used, there is no sensor for it and therefore it defaults at max temp. Has nothing to do with performance. I would put the 19 back on and see what it runs. I would also put a fuel psi gauge and check it.

The motor has fast burn "vortec" style heads therefore they do not use a lot of timing, especially with 87 octane. From a scan tool stand point, it looks normal so either your over propped, have a fuel delivery issue or ignition issue.

hi guys, thanks a lot for the suggestions. I have since found the problem, a bad spark plug cable. Changed it and went right up to 4800.

Again, thanks!

Ha, that was gonna be my suggestion, either cable, coil or dead plug. Glad it was that simple....troubleshooting aside.