I hope for some much needed advice on this problem.

I have an 88GL which actually meets the electrical
specs of an 87 by looking at the Bentley wiring diagram.

My problem is this:
When the engine is cold it seems to run fine.
At highway speeds all is well until the engine
reaches operating temperature.  After the engine
reaches operating temperature it begins bucking
during upshifts and throttle speed increase. When
I push on the throttle to increase speed there is
a significant hesitation.  The engine speed will
finally increase to meet the fuel demand and throttle
response. Engine speed above 2500 seems ok.  Throttle
increase above 2800 RPM seems normal(no hesitation).

I am thinking this is an Oxygen Sensor GROUND problem
but am not sure.  I have read all the posts concerning
oxygen sensor grounds and I have questions.

Where does the oxygen sensor ground(green wire)?
Does it go to ground at the #29 chassis ground by the ECU?

I have a three wire oxygen sensor.  Where does the brown
wire ground from the oxygen sensor(chassis harness). The Bentley indicates
a ground at #12 ground in engine compartment(left). The brown wire
on my 2.1 02 sensor goes into the engine compartment harness which
runs along the front of the engine deck. I cant tell
that the brown wire goes to ground from the 02 sensor.

I have cleaned and reinstalled all grounds, however
I combined some of the grounds at two locations on
the left engine firewall.

I have a 2.1 Boston Engine installed in MAR 2008
New AFM
New Idle Control Unit
New 02 sensor
New Distributor and Hall sensor
New ECU
New Evaporative control canister

This problem has got me down!
As you can tell I've replaced just about all components.
I also have the harness installed between the AFM
and original chassis harness.

Thanks for any advice.

JB 88 GL Guido
New spark plugs, cap, rotor and wires
New fuel injectors and fuel lines
New fuel pressure regulator