75 914 with D-Jettronic, need help diagnosing stuttering Options

[Rant6]

Hi folks. I have a nearly all original 1975 914 with the 2.0 engine. The car has 93k miles on it, and I have owned it for almost two years. I have been troubleshooting one particular problem for quite some time. The car runs perfectly with one exception. The engine hesitates or stutters often. It is a hard stutter, that is, it actually feels like maybe the ignition is cutting out for a fraction of a second, and so it causes a bucking sensation when driving the car. There are few discernible circumstances where this always occurs or never occurs. It seems to be random, and it can occur under easy acceleration, steady throttle, or off throttle (usually VERY slightly off throttle). It can occur under cold or hot conditions. It happens every time I drive the car, sometimes infrequently, but more often it happens constantly. It seems to happen most often in the middle of the RPM range, that is from about 2500 to 3200 RPM.
Some of the emission control stuff has been disconnected or removed from the car including the charcoal canister, the distributor vacuum retard, (I don't think there was a vacuum advance because I can't find where the hose would have connected to), the vacuum line to the decel valve, and an electrical 2-prong plug that goes into the intake plenum. I have done the following things:

Fuel injector cleaner
New plug wires
New plugs
New rotor/cap/points
New air cleaner
Re-attached the electrical plug in the intake plenum (this caused the idle to surge up and down 1200 RPM, so I disconnected it - what is this thing?)
Re-attached the vacuum line to the decel valve
Replaced the circuit board in the throttle position sensor, and aligned.

I really thought the last item was going to be the fix, but it had no effect at all.
Can anyone offer some possible causes?

Thanks,
Mike

[r_towle]

There is an idle circuit that only activates in a single position.
The TPS is designed for many cars and many throttle bodies.
There is ONE way to mount it...its really not adjustable once you mount it correctly.
The pic is as mounted with the throttle body closed.
You can pull the throttle body with the TPS attached and set it up on the bench...no meter needed.
Use the picture below.