Hi,

I’m a 240 man so I still live in the world of a basic car with less frills! (:)
A 900 series was built up from basic and its still a good thing that is easy to work on with patience!

When something going on like in your descriptions the engine is already getting to much air to reach the higher RPMs above 750 to 800 limits. You say you are consistently on the 1000 rpm area.
On these cars with red blocks the IAC controls the idle rpm.
You need to listen to the start up and hear the engine “race up” past the normal idling point and go right back down to idle specifications.
If it doesn’t the IAC may be bad or at least dirty.

Like Blindboy is saying, check the throttle body plate for a full closure, as it may be exceptional dirty.
Check that a throttle switch is signaling a change of state reading when the plate just barely wiggles to open. An ohmmeter helps but I don’t know what type of switch you will have on a 900 series.
It maybe an on-off type or displays a variable resistance?
This switch tells the computer to hold idle speed with the IAC.
It also tells it to change things for powering up to pull away.

When you go into reverse the load is going to increase and this is where the RPM sensor comes into play. The computer is watching that closely, if the throttle switch is in idle position mode!
It’s a tight little circle or loop.
There is a start loop, warming up loop and operating temperature loop with a sensor that is in this scheme the whole time.
If there is a problem with that it could be telling the computer that you are all up to operating temperature. If you are not then you will be running lean or like too much air.
The thing to remember is in order for the engine to breathe air has to get in from somewhere!
Any air leak behind the AMM/accordion tube combination and up to the throttle is a suspect.

You see, there is a circle and you need to determine where the loop is broken.
It starts with listening to small details and eliminating air leaks and dirty adjustments!

It’s only after this procedure can you start thinking about a failed component someplace.

All we can do is start with a check off list that I have let you in on.
If you can fill in some maintenance “condition” history we can do a better job.
Any good shop mechanic will always listen to a customer, if he has coherent details!
Lots of times the person who lives with the car routinely senses something odd and that tells him what he can rule in or out.

Phil