I have a 90 crx with a d15b2. Current problem is between approx. 1600 rpm and 2300 rpm when holding the throttle is a set position the car begins to drastically change rpm down to approx. 900 rpm and back to where throttle was held. Sounds like fuel is being shut off and then restored. Surge condition continues unless you release the throttle and let it idle or increase rpm's. Unpluging coolant sensor, tps sensor etc will eliminate the condition. However you then get all of the associated ecu codes. Any ideas would be appreciated.

Thanks