I recently bought a 1990 civic with 117,000 original miles. Bone stock. It runs well but has rough idle (vibrations) and sometimes drops rpms at idle. Now my biggest issue is when I'm sitting at a stop light and tap the gas a cloud of smoke comes out. No smoke on cold starts or driving. Only after idling for a couple minutes. I'm thinking maybe valve seals? Already replaced pcv. I'm getting a oil change tomorrow. I literally just bought it. Just needing some help on this one. Thanks

 

You may have a couple of issues. Engine running issues could be dirty injectors, bad O2 sensor, fouled plugs. Valve stem seals would cause the smoke (assuming it is blue) off idle or on hi rpm decel. I had a low mileage 87 Accord that I chased a bad hot idle for a long time only to find dirty injectors (even as I had ran cleaner through the fuel).

 

Alright, definitely gonna replace valve seals this weekend, hopefully it will fix the smoking. Probably gonna clean the injectors tonight! Thank you for the response