Hiccup at 6000

[thstone]

I had the same thought as Maytag but I'll try to ask it another way:

If you hold the engine at 6K rpm, does the engine continuously "hiccup"? If so, this could be caused by a fuel delivery problem (fuel pump, clogged fuel filter, dirty injectors, etc). It could also be an electrical problem, sensor problem, etc.

Or if you hold the engine at 6K rpm, does the engine hiccup for a second, recover, and then run fine at 6K rpm? If so, this is not likely a fuel delivery problem. This is something transient like the intake flap, variocam, etc.