I purchased a 92 DA with a b20 swap last week and have noticed that after warm up or a 15 minutes of driving the check engine light comes on. Also the idle, during warm up, is 1500rpm's. However, during normal driving, I'll come to a stop and the idle will be at 1200rpm's OR they will jump between 600-900rpm's. What's up with this? Is it the ECU, or possibly the distributor? I'm at a loss as to what the problem is. All HELPfull answer's are appreciated !