1999 Johnson J40PLEEA engine problems.

I have a 1999 Johnson J40PLEEA engine. I have had the fuel system and carbs cleaned. Compression on both cylinders is 140 lbs. I've replaced the coil and CDI box and new plugs, but still can't get the engine to rev over 2500 rpm. Had mechanic out to look at it and he said it seems to be something electrical, but he doesn't know what it is. Does anyone have any idea what could be causing this problem. Any help would be greatly appreciated.

Sounds like fuel related, to me. But, it could be something not advancing the timing.

'99 40 is probably going to have SLOW mode. The key here is the 2500 limit that you mention. Is it very rough when you hit the 2.5k mark?
Look on the head for the temp switch. Locate the tan wire, and disconnect it from the harness. Should be a bullet connector.

Run it. If the problem clears up, you are either overheating, or you have a bad temp switch.
If you are overheating.....GET IT CORRECTED. Don't run it hot.

Better yet, get a digital temp gun and read the head temps directly. Should be in the 140 range. 208, I think, is the overheat point.