Got a strange problem where I'll start my car and the idle will jump all over the place. It'll jump up on the start like it's supposed to do then drop and almost stall and then just keep ping ponging back and for between 500 and 2500. If I put in gear it will either run fine once I get it going or it will stall. Also when I'm moving around a parking lot and it started that strange idle it'll harder to steer than usual (like the PS isn't getting any power)
I can't figure out whats going on. Theres no fix it light coming on so I don't know where to start. 9/10 times it starts fine but sometims it just doesn't want to wake up. One other thing is if it sits overnight or for more than say 6 hours it will always start fine. It's when i go to the store or a quick trip somewhere will it not want to start once it's been shut down for less than about 6 hours.
Lemme know what you think

 

If it's fuel injected the first thing to do is to service the throttle body. I had almost the same problem with my winter car the 91 Z-34 Lumina. Pull the IAC and clean all the TB idle passages with a commercial TB cleaner. Clean the throttle plate especially around the edge. If the IAC is more than 5 yrs old replace it. They get gummed up and get sluggish to respond to idle set commands from the ECM. The TG's won't set an SES light, later GM cars will set the SES light if the idle does not come up or down on command from the ECM within 50 seconds. Also inspect for vacuum leaks, they can cause erratic idle. In fact, most dealers perform TB service as part of regular service now.

 

When did this start? What did you do to the car prior? It sounds like it could also be a fueling issue. A lean mixture will cause the motor to go all over the place and have an uncontrollable idle.