Idling lower than 1,000 rpms. at high speeds,

Check for trouble codes. You can get this done free at most car part stores.

MAYBE CHECK (MAF) MASS AIR FLOW SENSOR

Can be caused by failing idle air control valve or by vacuum leaks or egr valve stuck open. See notes at link below.
Do It Yourself Diagnosis and Repair

You have a mechanical bind. Disconnect the main linkage and work it all by hand. Everything should be free and slopy. Aerosol carb cleaner will help, but only when the engine is not running.

Try cleaning the throttle body and check the gap on all the spark plugs also all electrical sensor plugs and battery terminals this could be related to engine temperature also if to hot rpms stay up longer to cool off but maybe your idle air control valve is bad when did it start?

the idele speed control valve is not working properly

why do you want your rpms higher while idling? you don't want them high because your gas bill will reflect that. slow shouldn't matter but if it's dying while on idle it could either be your mass air flow sensor or your fuel filter being clogged

Idle control valve...

HIGH DOLLAR PART, 400 to 500 smackers....

You can try cleaning it, I beleive that is the same 2.0 liter motor they put in the ford Probe? I could be wrong, I know they 2.0 has issues with the idle control valve..

Anyway, if you want to try cleaning it, try this link... its to a Probe, but should be the same as yours...

http://www.geocities.com/adamk01452/IAC_Clean.html

If its not the same as that, you can probably search the net and find a site specific to your car... but it really should be the same motor, even the haynes manual for the Probe has sections for both the Probe and 626 in it...

Good Luck!!!

the idle speed is controlled through the on board fuel injection control module (known as the PCM), even if u raise the idle at the throttle body the computer will slow it back down, however there is a problem that causes slow idle, do the following procedure to correct the slow idle issue, follow it exactly.

Here are some of the causes of surges, stalls at stops, slow idle speed, erratic idle speed, rough idle and engine hesitation (and other problems), it is in most cases the idle speed control air-bypass valve and or throttle valve and upper intake, these area's get full of gunk and combustion residue over the miles and cause idle issues (stalls, low idle) like yours, Get a can of intake cleaner from any local parts store, not carb spray, intake cleaner, it is made by a company called CRC, remove the air intake hose to the engine, hold the idle high so the engine won't stall, then spray the can of cleaner into the intake while keeping the engine running, use at least 1/2 the can, shut down the engine and disconnect the battery for 5 minutes, then restart and complete a number of mixed driving cycles, town, freeway, stop and go etc., after a few days the problem will go away as the system will relearn to the clean intake.

The PCM controls idle speed to ensure good driveability. The PCM will only attempt to maintain the desired idle speed when it “knows” the throttle is closed. A throttle switch or the TPS input is used to determine when the throttle is in the idle position. Motors and solenoids are used by most PCM’s to control idle speed. Many PCM’s are programmed to attempt to control the idle speed by adjusting spark timing and then by controlling the idle speed actuator. Some computers of the early 80's did not control idle speed.