I just had a similar problem on my 97 Type SH (123K miles). One dealer couldn't figure out the problem and told me that maybe there was carbon buildup on the valves and to try to run an engine cleaner thru. That didn't work. A second dealer finally discovered that the EGR valve was broken, so they replaced it AND they replaced my fuel injectors FREE OF CHARGE! I guess there is an extended warranty on some parts for emissions control, but I was amazed that they covered the car with over 120K miles on it! Anyway, that fixed the problem.

FYI for any Chicagoland Honda owners - it was at Castle Honda in Morton Grove IL. I was very impressed by their service department.