Well let me start by saying I have had the worst luck with boat shops . This is my first big bass boat and motor I own a 2000 nitro with a 200 opti on it I am the second owner first owner went though all the crap with recall etc. Anyway been a great engine. Have had it a lil over a year with not the first problem. Well about 3 weeks ago the motor had what sounded like a miss . pulled plugs looked really black so i changed them out miss gone at this point engine ran fine for about two outings . I was running back one afternoon I had been putting around alot so i thought Id blow her out Well at wot I notuced a slight drop in rpms and lost 7 to 10 mph off top end . Well done everything I could bye the service manual. No change took it in to the dealer ooooooo no not the dealer , Well after about 2 weeks Im told well its the thermostate on the port side stuck open that sides running to cool causeing the power loss . Well I can go for that How much ummm about 300.00 cause mercury does nat make the 120 therm anymore its a 130 and you have to have the new covers. Well I mean if you say so i guess fix it. Well get a call your boats ready but Its showing a tps fault on the ddt ?????????? I ask umm your just now seeing this . Well it just happened I was running the engine after putting in the new therms and it just stut off and wouldnt crank back up ....umm do what my next question. Well the manual says if theres a tps fault youll get a beep from guardian and a reduce in power ,so none of which is makeing sense ,but anyway the just is Now my therm problem is fixed i guess cant tell a diff in engine profor, And Im being told I need a tps another 180 dollors plus 1/2 labor , I felt like im getting hosed So i go to another dealer he explain what Iv been though he hooks up ddt showing tps fault . before i spend more $$$$ my question is can a weak tps or going bad tps make me loose the top end, or any ideas The following have been checked 1. Compression check 90 psi all 2.Fuel pres check. Normal, 3. thermostats 4. spark plugs 5. coil packs 6. new fuel in tank 7. Batterey voltage 1000ca 8.injectors normal 9. Fuel rail no leakage 10. Fuel bulb staying firm 11. Air compressor normal. Please someone help me I just dont trust these boat dealers I understand they half to make money but Man its one thing after another . HELP