Engine revs up/down on its own

[jondee86]

You could try unplugging the TPS, and see if it makes a difference.
And also try unplugging the MAP sensor.

With the TPS the main thing is to check that the IDL switch actually
opens when the throttle is fully closed. You need to find the correct
pins and check with a meter.

Check the idle air bypass screw... down the tube on the side of the
throttlebody... turn it all the way clockwise (closed) and see if it makes
a difference.

Check the cooling system has no trapped air... park with the front of
the car up a slope. Run with the radiator cap off for a few minutes
until the thermostat opens, to let any trapped air escape.

Look everywhere for vacuum leaks into the inlet manifold. What head
(bigport or smallport) do you have on the engine ? What inlet manifold ?

Cheers... jondee86