Hello guys!

I recently had a great deal on a 100 C3 2.5 TDI. I am quite unsure if it is a 1T engine code or newer C4 style engine AEL as both appear virtually identical. I had a few problems with the crankshaft gear slipping which has been taken care of.

The car developed a weird problem about 5 days into owning it. Car when cold, starts up instantly, drives like a dream, tho a BIT knocky but that's expected from an old diesel. When the car warms up (on the dash its 75-80c) as the running temp, if cruising on highway or cityroads, the speed or RPMs do not matter, the car starts cutting off and on REAL quick. Power is present. Its like a quick stutter, which randomly clears and seems to be fine for a while and at times is so bad its shaking the whole car unable to accelerate.

The fuel filter is not original as it is impossible for one to be found new (Replacement newer style filter), tho it shouldn't be an issue as its running perfect cold.

It also tends to randomly lose power when accelerating almost like the turbo loses power but it can be heard whistling as it should (?). In this scenario car behaves as the turbo quits, like a naturally aspirated engine with no stutter but power loss.

So far tried checking the pump connectors, pump timing (?), wiring seems to be fine as I shaken the whole wiring loom to check if its cracked.

This problem was gone for 2-3 days after replacing the alternator regulator and shielding the B+ cable, but the problem quickly got back.

Possible power problem, tho may not related, turning on the Digital AC unit, the lights shine fine, turning on headlights makes the AC unit go VERY dim and slowly come back to "normal", although a bit dimmer than without lights.

I would truly appreciate any help as I am clueless as well as a few good mechanics I know.