Hey that's great that the new parts are working out, your RPM guage gets it's signal from the alternator, check your wiring, plug that is into the alternator, it's connection is through the regulator (inside the alternator) could be regulator problem, or many other places. Somewhere to start.
Last edited by grancito; 08-15-2007 at 02:18 AM.
1994 6.5 turbo GMC K2500 HD suburban "F" VIN FSD heat sync #9 resistor, PMD in the bumper, no cat, mechanical waste gate, 220,000 miles, 4L80E Positrac 3.73 diff, 17 mpg highway.
1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.