93 Civic coupe idle problem

I was cruising with my sister in her 93 civic coupe (D15B7 + auto tranny) and while stopped at a red light her idle speed dropped to the point where the engine almost stalled. There are no trouble codes to work with and the electrical load was constant with the radio on at low volume and the headlights/parking lights on (rad fan was not on when this happened). I told her to rev up the engine to prevent a stall and the car ran fine afterwards. After this incident she told me the same had happened to her some six months ago or so. The car is in top shape as I change the fluids/filters and tune the car on a regular basis.

I suspect the EGR valve or idle regulator (the distributor is not loose and the timing belt was changed 10,000Km ago). The head gasket has already been changed earlier this year and is not leaking at the moment (no oil in the coolant or coolant in the oil pan). I also cannot find any loose connectors in the engine bay; or any leaking vacuum lines (leaking vacuum lines do not usually cause intermittent problems).

Does any of this sound familiar to anyone? I will check the above mentioned "usual culprits", but I would be greatful for any additional hints.

Thanks... hope this extensive explanation did not put you to sleep :thinkerg:.

Just adjust the idle adjustment screw on the throttle body and raise it to the specified rpms. I had a problem because my throttle body cable was sticking one day and the idle was at like 1200 rpm and it would suddenly drop to like 200 when it did not stick. Lots of things can happen but just ask people around your away who know their stuff and can explain it to you better than someone having to type out a report telling you what it could be.

LOL Thanks for reminding me to shampoo the engine. I am a :loser: since I checked everything other than the throttle spring mechanism. That could very well be the problem since everything else I could think of came within factory specs.

I obviously have too much time on my hands....