Did you solve the problem yet? If not, it's probably a faulty Frequency Valve C since my '88 Accord had the exact same problem several years ago. I did some troubleshooting and discovered that my Frequency Valve C wasn't working properly.

I bought a used one from Matta Motors(www.mattamotors.com) for around $40 and I was told it was a very common problem on 86-89 Accords.