K2500 5.7L no codes misfire

98' K2500 5.7L:

Intermittent misfire

Started out with an engine light-P0339A-Intermittent Crank position sensor malfunction(replaced twice).

Still has an erratic misfire.

The only weird thing I noticed(by use of a scan tool) the RPMs will spike at 7500 RPMs(at idle). Should I be looking at a camshaft position sensor problem? Distributor problem?

Any help or information would be appreciated. Thanks.

The rpm spike on the scantool would suggest it is still a problem with the crankshaft position sensor or its wiring. The VCM uses the crankshaft sensor for rpm readings because it gives a signal 4x per revolution versus the 1x per 2 crankshaft revolutions it would see with the camshaft position sensor signal

Check the crankshaft position sensor connector for loose pins and double check engine grounding points

If I'm not mistaken, the engine computer governs the max RPM's in park to prevent damage.