It is normal for RPMs to stay high until speedometer is under 5MPH, it lowers emissions
Also when shifting gears RPMs should hang high for a few seconds when clutch is in.
When AC is on idle will be higher, that part is normal, but 3,000 seems excessive unless that's where you were at when clutch was pushed in.
Computer knows your speed so will hold RPMs high until speed goes down, but generally for only a few seconds, maybe 5 seconds, but it will stay above 1,200 until below 5mph
TPS is throttle position sensor, but while it might cause it I would think not since it can't really "control" anything, it is a sensor.
The IAC(idle air control) valve is what the computer used to set RPMs, it is an air valve that by passes the throttle plate, like a controlled vacuum leak.
Computer adjusts this valve to set RPMs, this is what is used to hold RPMs high when above 5MPH and when shifting gears, and computer opens it a bit more to increase idle when AC is on.
They are not hard to clean, and because it is a moving part it can get sticky after a few years.
Also check throttle itself, it does have a return spring on it, this has to be strong enough to pull the throttle plate closed against the air flowing into the engine, if it gets weak the throttle can hang open even though gas pedal is released.
Lube throttle cable as well they can get sticky
If you have cruise control, that's another cable that can hold throttle open longer than it should.
And just as a heads up for fuel injection and manual trans, never coast downhill in neutral, it will cost you money.
Nice thing about fuel injection over a carb is that the injectors can be shut off for 0 fuel usage.
So if you are going downhill in gear, foot off the gas pedal and RPMs are above 1,400 computer will shut off the injectors, 0 fuel use, if you push in the clutch and RPMs drop to around 1,100 computer restarts injectors.
With a carb you did coast to save money, it's opposite with fuel injection
Last edited by RonD; 07-04-2016 at 12:14 PM.