Has been idiling "not-so-smooth" for some time ; check engine light= o2 sensor, replaced- ok... ; 190,000 miles on engine; still idles semi-rough, "gassy" exhaust smell, fuel pump went/replaced. hesitating/bucking on acceleration in drive---however, when in low, much better--strange to me. Changed plugs and wires about 6,000 miles ago... any thoughts-- thanksalot...

Sounds like maybe dirty injectors.

Replace the plugs and wires, have the ignition module and coil packs tested. Clean out the upper intake plenum, and run some feul injector cleaner in it.