I have potentially the same problem w/ my 92 Civic Si. The car has developed a hickup every so often in 1st & 2nd gear.

the car bucks a little in those gear. Not smooth engagement anymore. @ Speed, every thing seems fine.

I notice occasionally, not all the time, a slight skip in the idle.

It doesn't feel like it will stall but is annoying & makes me feather my clutch a little too much for my liking.

Also noticed a sulfur smell eminating from exhaust after exiting recently. & lots of ticking noises from exhaust after engine shut down & exhaust rattle @ cold start. Don't know if these things have an affect...

Spark plugs & fuel filter have all been recently replaced. K&N shortie Air Filter cleaned recently. Otherwise, all stock.

Any insights would be gr8! Thanks.