Symptom #1: RPM variations. After the engine is warmed up and I am stopping at lights, say, every mile or two, the RPMs will be 2000 then the next light it might read 1500. It's kind of a crap shoot for what it will read. It doesn't stall, or race, but there's always some variation within a range.
Symptom #2: Bucking. You know that movement when your not accelerating but not braking either? Kinda coasting? My car doesn't coast, it bucks. Not severely, but it's there.
Symptom #3: Hard starting. Almost always when the engine is hot, and sometimes even when it's cold...sometimes it won't start at all and I have to wait a few minuts to get it started. Turns over like the dickens, but just doesn't want to catch.

A few days ago I pulled the plugs and found them all suited black. I cleaned and regapped them, and then leaned the fuel mixture on the SUs by 3-4 flats. But all symptoms remain intact.
Any ideas? Please have an idea.
Thanks.