2000 c40tlry issue

[outboardilliterate]

I can't get the engine to rev over 3700 rpm. When I apply full throttle it runs fine for a few minutes then it starts loosing power. I can reset the throttle to neutral and apply the throttle again and it will run fine (at 3700) again for a few minutes then do it again. I have checked.the fuel system and the timing, any other suggestions.

[99yam40]

Check compression on all cylinders and the spark.

How did you check fuel system and timing?
And what did you come up with?