1973 2.0 D-Jet Hesitation Stumble 2500-3300 RPM Options

[gonzo54]

I had this problem shortly after I purchased my car in 2019 and I solved it with a new 2.0 914 Rubber TPS Circuit Board.

Fall 2022 I rebuild the motor to a 2056 with a mild Webcam 73 (D Jet compatable) and The Hesitation Is Back. So far I have accomplished the following using PB Anders articles and with the help of Bob D @bob164 who has logged numerous hours on this project.

-Checked the resistance of the entire engine wiring harness repairing and improving resistance on several connections. Checked all grounds. No Hesitation Fix

-Smoke tested the intake which found a leak at the Cold Start Valve, fixed. I still have a minor leak at the Throttle Body shaft and #1,2 Intake Manifold (replaced gasket and added sealant - needs resurfacing) No Hesitation Fix

-Fuel Injectors were sent to Mr Injector for cleaning and flow test during the rebuild.

-The Dizzy was disassembled-Trigger Points cleaned, Weights cleaned and lubed, Vacuum advance checked. No Fix, so I bought a 123 Blue Tooth Dizzy after reading about Trigger Points possibly being the problem. No Hesitation Fix

-The CHT sensor is within the paramaters of PB Anders data.

-The MPS checked out and did hold vacuum withing the leakdown parameters but it decided to quit holding vacuum so we rebuild it with a Tangerine Racing Kit and PB Anders data. No Hesitation Fix

-The ECU 0 280 000 037 that came with the car was replaced with ECU 0 0280 000 044. I've read that ECU's rarely fail. No Hesitation Fix

-TPS: All of the 914 World threads regaring this problem takes me back to the TPS and TPS Circuit. I now own 2 complete TPS's 0 280 120 032 and 4 circuit boards. I've tried all combinations including the 914 Rubber TPS Circuit Board and the Throttle Switch has always been set up per Ralph Ricks Instructions. I still have the Hesitation. When I disconnect the harness plug to the TPS The Hesitation Does Not Occur! The car has a little lag with the TPS harness unpluged but accelerates through all RPM's with out a problem. This test continues to lead me back to a bad or dirty TPS Board. I have cleaned and sprayed the boards and sweep fingers with electronic cleaner numerous times, perhaps the gold plated contact fingers are too warn but a continuity test as the fingers run over the track appears good. I have rechecked the TPS harness wires to the ECU and they check good.

I do not want to continue buying parts that may not fix this problem, so at this point I'm Stumped! Should I buy another Board or complete TPS or go in another direction? This is a great group with a wealth of information what do you think?

Thanks in advance,