97 Passat TDI Runs Rough After warm up: No codes

[vwzzuk]

1997 Passat TDI: 1Z/AHU

Problem:
Starts and runs fine when cold. When it warms to about 100 degrees (Coolant Temp) on the scanner, it starts to run rough and jumps around in the engine bay. Increase throttle to 1400rpms and above and it runs fine. Allow it to idle, and for a second its OK but then immediately returns to rough idle. The odd thing is that there are no codes. I do get a blinking glow plug warning light however when it starts to run rough.

I've swapped out:
fly-by-wire unit, ECT sensor, ECU Computer, measured 3rd injector (reads at 108 ohms). EGR is deleted with no issues or codes.

Just swapped out the MAF and IAT sensors. Still remains the same issue. Hummmm.

Any suggestions?

Thanks, Dave.

[vwzzuk]

UPDATE

OK, the problem is solved. It was the Quantity Adjuster inside the pump. It needed the "hammer mod" to bring it back into specs.
Learned about this from Joe at Double J in Portland who fixed it.

Thanks Joe!