I have an Aurora.. It is not idling correctly. It sometimes will not shift gears until the 3000 RPMs, and it tries to die when you come to a stop. I have had the transmission rebuilt and replaced, the fly fixed, changed the spark plugs, and put a motor/gas cleaner in the system. Help please.

In park or neutral not much load on the engine, when you put it in gear, there is a load. How may miles on the engine? How long since a tune-up? Any applicable trouble codes? Check and clean the idle air system and throttle body, see if it helps? Check cylinder compression. If the compression is way low, it may be tough trying to get it to run correctly.
In the old days, carbed engine, no computer, sometimes we'd set the idle in drive, at least it was driveable, it wouldn't die every time you stopped at a stop sign or red light. Yeah, when you put in park or neutral, the rpms would go high. Sometimes, your just trying to keep it on the road, if possible.

Have you checked fuel pressure, and is the check engine light on now ?

Sounds like 2nd gear in the transmission is slipping. Cars usually shift at 15-20 mph from first to 2nd. First check the trans fluid.

One problem is IAC it is sensor beside TPS (RPM).That is 35,42 really do worry for now.

Sounds like a shorted or sulfated battery to me.

Please replace your COIL with new one.
Regards, Jay

check your IAC or stepper motor operation run the vehicle with the AC on and see if its makes a difference

check throttlr sensor

idle air control motor or just a plain old vacuum leak

your idle speed too low.take it to a dealer.they have to reset idle.it should be 600-800 rpms.when you turn on air conditioner.the computer steps up idling to keep engine from stalling .your curb idle too low.