Problem is not getting fixed and very frustrating. Engine ran great at the beginning of the year(April). Then in early May the engine started to stumble when throttling up. I have a 2000, 150 efi Merc. It has seen 2 Merc dealers so far and a new stator, cdm's (6), throttle position indicator (2). The stumbling used to be through the full range, but now starts at 4400 rpm. 3/4 throttle. As soon as I put the throttle to full speed, it stumbles and does not run smooth. if I throttle back below 4400, engine smooths out. The second Merc dealer tested the TPI and said there was a bad spot on the switch at the 3/4 position. The new TPI was replaced with another new one, but it did not solve the problem. Tired of throwing parts at the engine. Does anyone have any suggestions?<br />Thanks, 
<br />John
<br />John