Possibly bad thermostat - don't know for sure
 

Hey, my car is a 94 RS and i find that when i drive my car, after i let it warm up for a good few minutes, where the temperature guage is right inbetween hot and cold, and the heater is blowing hot air - the temperature guage gradually goes back down to cold, and the car begins blowing lukewarm air as if it was just started, and the car begins to selve rev again at 1500-2000 RPMs when idling. And the only time the temperature guage goes back up to centre is when the car is idling. Whats the problem here?

thermostat.

why u up so late :O

^^^ stalker....

ur car blends in with night not mine. i wonder why...

change yur thermostat and do a coolant flush as well man

Check coolant level.

yeah the coolant level is fine, but it still does that - i'll get the thermostat looked at and see if it is that

thanks alot!

New thermostat's not even $20... Might as well change it if your in there. And do the flush; or at least a drain and fill.

$20 for 5 litres of coolant...

To flush the system, first completely drain the radiator, and the block. Then, remove the upper radiator hose, stick your garden hose into the rad, and aim the upper rad hose into a drain tank of some sort (a bucket will do fine).

Turn the hose on, and once the rad is filled, turn the car on (be safe!! watch the fan blades). Once clear water is coming out of the rad hose, it's safe to assume your system is flushed. Turn everything off, drain all the water, and fill her back up with 50/50 coolant. Follow through with the bleeding procedure to ensure no air bubbles are trapped.

This isn't by any means the best way to flush, but by far the cheapest, and easiest.