Shifting gears causes a jump to 1,500-4,000 RPMS
Putting in park it idles about 2,500-4,000

It will randomly cut off while driving, stopped, ETC.

Bad Fuel Pump?

Idle Air By-pass?

Halp?

You been driving it like that?

That has to sound awesome when you shift into drive.... KerLUNK

I've owned the car for 2.5 days, and it happened all of the sudden, it got worse on the second half of the day. Day 1 No problem. Day 2 No so good, day 3 is no good at all

no check engine light?

None.

sounds like the idle air control valve possibly. they are around 30 dollars. if not that then throttle position sensor they should be in the 40s.

Possibly a Crank position sensor?



*UPDATE*
Was running 93 in it, Ran for shit, put 89 in it, so far so good. Any idea why that may be?
Going to do a Double Oil Change, Penzoil due to the Harsh Detergents, to hopefully break anything in there loose,(400 miles, or a week worth of driving) then probally Valvoline each with a can of Seafoam.

if that car was tuned for 89 take that junk back to where ever you bought it from

Possible dirty throttle body