i know what you are going threw my 93 did the same stuff. it is usually your egr ports in the back of your motor. check out tech2tech.net it tells you what to do about it. i did it and it fixed the problem and ran 1000000 times better. if you cant find it on tech2tech tell me and i will tell you how to do it,but they have pictures and everything. but i am about 99% sure that is your problem accords from90 to 93 are the worst about it. it is a cheap fix. all in all it will cost you about 15 dollers and some time. let me know peace brianb