Well, i just replaced the o2 sensor and the problems are the same.

This engine should pull from 1300 rpms without protest. I get clutch
chatter and bucking from 2300 rpms sometimes.The lower the gear , the
sooner the bucking. It does run fine for 30 seconds or so when I start it
up,so it seems to be a sensor/fuel injection problem..

Should I disconnect the throttle switch? I did that yesterday. Little
change,once again.When I installed the new throttle switch, it was right on
the money,but I got bucking.ECU? AFM? Vacuum leak? Wire broke in the
distributor? Vacuum advance,or mechanical the in distributor? Water
tempature II? Ignition timing?Cant think of anything else.

It seems like a switch. When my foot in just touching and releasing the
accelerator(like in a parking lot)a switch seems to click on and off.Jerk-
release-jerk-release, as the throttle is  feathered.Same at higher speeds.
When decelerating, from say 20-40mph, and then slightly accelerating again,
I can feel the jerking,but it is muted a bit as the speed and momentem
compensates.

Like I say, this started when I replaced left bank head gasket While doing
this, I cleaned those ground wires under the a/c compressor.The distributor
plug was removed ,and plug wires removed. I removed the intake runners and
fuel injectors from the intake ports, but not from their hoses.Any more
ideas what could be the problem?