Debugging stumble on acceleration when warm Options

[solex]

On my past few drives the car has been stumbling when I accelerate specifically when warm and in every gear except first, in my 2.0L D-Jet in a 75'

A few of things to note:
- Ground strap at transmission has been cleaned
- Installed a second ground at battery ground point to the engine fan
- New spark plugs Bosch W175T2
- Engine compression 134-145 all cylinders
- Fuel pressure set to 28 psi
- spark plug new wires
- 123 Ignition curve 2 with vacuum advance attached, 10 degrees advance at idle
- Injectors have been rebuilt by Mr. Injector
- All vacuum hoses have been replaced
- AAR is in working order and has been oiled

Not really sure where else to look, the engine idles < 1000 but is not smooth at times jumping +/- ~ 200 RPM

Any advice would be appreciated.

[solex]

This evening I did several things in attempt to further debug my problem:

1) Adjusted the TPS again using continuity on my DVM, based on the German site translation of https://jetronic.org/index.php/de/autos/d-j...Leerlaufkontakt (NO RESOLUTION)

(2) Adjusted fuel pressure to 30 PSI (NO RESOLUTION)
(2.1) Adjusted fuel pressure back to 28 PSI

(3) Advanced the timing beyond 10 degrees static timing. The problem was minimized but the stumble was still present, but with added problem of a high idle ~1300 RPM
(3.1) set timing back to +10 degrees at idle

(4) Pulled the plug wires one at a time to see if there was an effect, and there was. The wires when grounded generated a nice spark. I had previously tightened the connectors, the were loose even though the wires are new

The engine is just not idling smoothly and I went back to the advice of this forum that there must be a vacuum leak - even though I had replaced all vacuum lines earlier this year.

(5) Checked all vacuum lines again and did not notice any problems.

(6) Sprayed brake cleaner near at throttle body (TB) gasket. I noticed a change and at one point got the engine to stall. I tighten down the TB but the idle was the same.

I also remember reading here that the plenum can be leaky. I sprayed brake cleaner under the TB mount on the plenum and think I found a leak between the plenum body and the TB, the engine stalled after a liberal amount of brake clean a few times.

Any thoughts/confirmation before I remove the plenum this weekend?

[rjames]

This evening I did several things in attempt to further debug my problem:

1) Adjusted the TPS again using continuity on my DVM, based on the German site translation of https://jetronic.org/index.php/de/autos/d-j...Leerlaufkontakt (NO RESOLUTION)

(2) Adjusted fuel pressure to 30 PSI (NO RESOLUTION)
(2.1) Adjusted fuel pressure back to 28 PSI

(3) Advanced the timing beyond 10 degrees static timing. The problem was minimized but the stumble was still present, but with added problem of a high idle ~1300 RPM
(3.1) set timing back to +10 degrees at idle

(4) Pulled the plug wires one at a time to see if there was an effect, and there was. The wires when grounded generated a nice spark. I had previously tightened the connectors, the were loose even though the wires are new

The engine is just not idling smoothly and I went back to the advice of this forum that there must be a vacuum leak - even though I had replaced all vacuum lines earlier this year.

(5) Checked all vacuum lines again and did not notice any problems.

(6) Sprayed brake cleaner near at throttle body (TB) gasket. I noticed a change and at one point got the engine to stall. I tighten down the TB but the idle was the same.

I also remember reading here that the plenum can be leaky. I sprayed brake cleaner under the TB mount on the plenum and think I found a leak between the plenum body and the TB, the engine stalled after a liberal amount of brake clean a few times.

Any thoughts/confirmation before I remove the plenum this weekend?

Order new intake runner hoses if you’re going to remove the plenum. Your old ones are likely shot if they haven’t been replaced in a while. Plus trying to remove them without destroying them isn’t worth the hassle.