GT40 Barely Running after Warm Up

So have inherited my brother in-laws 2000 Air Nautique with the GT40. The boat has been to most marina's in northern Indiana over the past several years trying to chase down an issue but none have figured it out.

Most of the time, probably 8 out of 10 trips on the lake the boat will barely run after it warms up. Normally it won't do it unless the temp gauge is reading over 160, but today it did it with out the temp gauge reading 160 (think it was reading around 155ish). The red light on the dash in between the gauges does not come on when the issue is happening. Basically, when it happens, the engine sounds like it is struggling to run. The rpm's surge some on its own and it occasionally sounds like a slight backfire (popping sound). This morning the belt was actually squealing some after it acted up. Sometimes the issue goes away and you can drive the boat just fine and sometimes the issue persists and you can barely get it back to the lift. I know the coil and IAC has been replaced this summer. When I say it warms up, I am watching the temp gauge on the dash and once it stabilizes, typically around 160, I am considering the engine at its normal operating temp. It does not act up at all while it is cold

Thanks in advance!

protonvx wrote: The boat has been to most marina's in northern Indiana over the past several years trying to chase down an issue but none have figured it out. I know the coil and IAC has been replaced this summer. When I say it warms up, Thanks in advance!

Cliff,
Do you know what else has been done at these marinas? It would be helpful to know.

MrMcD wrote: When I purchased our 1995 GT40 Ski Nautique 4 years ago it had similar issues. I thought ours was going into the Limp Home Mode, designed to save your engine if it overheats or loses Oil Pressure. Mine was not hot and had good oil pressure but I changed the Temp Sending unit and there was a second oil sending unit that signals the computer all is OK. Changing these fixed my engine.   When you gave it gas it would really sound nasty, like it was chugging or coughing.   Not smooth, no power, like you I felt lucky to get back to the dock.   It has not had any issue since then. Someone on this forum steered me to my repair.   Good Luck

Thanks! I will order these sensors and see if it helps...

There is an oil pressure sender also tied in I believe.
I went back and looked and can't find the receipt for these parts to give part numbers.