I own a 91 rx convertible. When i start the car after it has cooled off, it revs up to around 2500-3000 rpm's. Within 30 seconds after starting it will go down to 2000 or so rpm's. As it gets warmer the revs drop closer to idle. When it drops to around 1300 and the car is pretty much warmed up, the revs will jump from about 1300 to 800 and back again to 1300 until it is finally warmed up and it idles smoothly. The car idles good at 750 rpms. Is this too low? Is something faulty that makes the car do this? I've had the car for about 8 months and it has done it since i got it. If anyone has any ideas what the problem may be, i would greatly appreciate any feedback. Thanks.

 

thats pretty much normal

 

Check the adjustment of your TPS. Its just a pot/resistor which means they age and its values aren't linear as when the car was new.

 

Setting the throttle position sensor should help with the surging. You will need to make a three prong connector with two LED lights. I believe there are instructions on www.fc3s.org.