I am new to this forum but an experienced boater and with good knowledge of the 5.7. I have a 2001 Stingray 22’ bowrider (220LX) stock 260HP 5.7 EFI TBI. New plugs, wires, distributor cap, fuel/water separator, new battery, fresh marine synthetic outdrive oil, timing set exactly at factory spec 8 deg BTDC and procedure as per factory manual, fuel injectors work perfectly and have been cleaned, fresh fuel in tank. Fuel pressure also tested between the high pressure pump and the TBI = 38 PSI. Compression. Is good at 162 +/- 2 psi on all 8 cylinders. The return line is clear and does not have an anti-siphon valve (factory)

However, I cannot get max rpm unless I am running wide open throttle for at least 2 minutes straight 4150 rpm and then it literally jumps to 4450 rpm, like it just let go and I achieve 61 mph versus 55 mph GPS! This is a 23” Ss prop. I have the same symptoms when I use the 21” prop. ( it jumps 300 rpm after WOT for at least 2 minutes) and also I tested a 19” prop. Same symptoms. It’s also slow and bogs out of the hole. I am in Las Vegas, elevation 1100ft at Lake Mead

I don’t know if it is a fuel pressure issue, or an electrical problem that kind of cures itself at sustained high rpm. Or would a gimbal bearing cause these problems?

Also, just this last weekend I had a no start issue at the end of the day (105 degrees). I checked and had spark but the fuel injectors did not spray like they normally do during start. So I removed the fuel supply line on the back of the TBI, cranked it over and hardly any fuel was coming out and then it blasted a bunch of fuel. Connected the fuel line back up, and it fired up right away. It was a Vapor Lock. Strange. I’ve been out on the lake for the temperature was 115° and no issues with starting. I wonder if this has something to do with my problem? Thanks for all your help.