Hi All,

After I read the information on Jim's webpage and the web, it can be two possibilities: wire insulation and/or the reference potentiometer of the ETA. I just rewire to see whether it helps. I also have plan B to buy the new/rebuilt ETA. After google the web to see the availability/price. One company seems to be very good knowledge of the ETA and it is: http://www.jaytanindustriesinc.com/MercedesBenzTB.htm
I ask the guys how they rebuilt, here is what they email me:

Hi-Hi, Mr. Tran,

Our remanufacturing process,concentrates on four distinct areas to insure you are
purchasing a,"AAA" unit in both quality and value.

1. POTENTIONOMETERS "A" & "B"
a. The values of each of the four black traces on each potentiometer must
equal a pre set value.
b. Example: if potentiometer "A" value is x and "B" value is y then the addition of
the two must equal the value y. "A" tells the ECU how much the throttle plate
is OPEN "B" tells the ECU how much the throttle plate is CLOSED.
2. STEPPER MOTOR
a. The integrity of the motor to actuate movement of the throttle plate.
3. ELECTRONICS
a. Ribbon cable, IC board and wiring harness for opens, shorts and
potentiometer weakness failures.
b. Throttle valve switch which confirms with the ECU, the open or closed position
of the throttle plate.

4 MECHANICAL
a. Linkage, bearings, throttle plate and shaft for binding, sticking and hesitation

Finally, we make the unit look pretty. Is pretty a good word for an auto part?

Each of the four areas are certified OK, repaired or replaced as required.
The electronic throttle body is warranted for 2 years no mileage limit.

Please, feel free to contact us with any further questions or needed assistance which we may extend to you, our client.

Terry O'Connor

I hope the information that I post would help any one who has the same problem as I do.

Cheers,