Intermittent power loss

Driving home and loss power...stepped on the accelerator and nothing happens. After the car sits and cools down to below 160 (about 15 minutes). It fires back up like nothing was wrong and and goes until it get to around operating temperature 190 or so and then it starts losing power again and eventually dies.

I have checked vacuum lines. Already replaced the one in the computer a few weeks back. I plan on swapping n75 with one from a formally working car. Will also change fuel filter. May also swap out the MAF. The EGR was deleted by a previous owner.

This did not seem to be limp mode to me...and there was no CEL. It would have power and run fine then would start losing power and eventually poop out. I have not hooked up vagcom to see if there are other codes yet. I also noticed bottom radiator hose was not getting hot...so perhaps thermostat has a problem, but it doesn't seem likely that would cause those symptoms. Temp gauge never went above normal and seemed to warm up fine too. Heat was working fine. Nonetheless it seems temp related because it starts right up and goes once it cools off a bit.

Anyone run into this sort of problem before. Any Ideas? Any suggestions other than the plan above?

Bad throttle potentiometer? Scan it.

-Todd

How would it not overheat if there's no flow through the radiator? I'd change the thermostat soon. Maybe your coolant temp sensor is in a bubble? Is the water pump pumping?

Agreed. I bought the car (sedan with less than 200k) cheap a couple of months ago after my b4v was rear ended. I got a timing belt kit along with a thermostat and water pump. Just no time to do the work. I plan on flushing coolant, doing the belts, and new fuel filter. I thought I read something about it being rare for these thermostats to fail closed...but who knows. I will also swap out the temp sensor. I have lots of good parts on my wrecked B4V. I will report back when I have that sorted.

Wait... is it just losing power or is the engine shutting off. If it’s actually doing the latter, I’d expect a restriction.

Check the fuel filter, as mentioned. Kinked hoses, etc.

-Todd

Yep. My first thought was a fuel restriction. The car would just die. Other, possibly unrelated symptoms, like the fact that it seemed to run fine after it cooled down made me think twice, or at least consider other possible causes. I should be able to figure something out this weekend.
Thanks everyone for chiming in. I don't think I would have gotten another one of these cars (I have three now...actually four if you count the wreaked one), if the helpful experienced folks on this forum weren't there as backup.

Swapped fuel filter and no change. Pulled codes and there was a 00575 - Intake Manifold Pressure...so next is vacuum hoses and n75 swap. Engine temp was 87 degrees C.

Swapped n75 and hoses but that did not fix it. Same problem. Car heats up and then has intermittent power loss. By intermittent I mean the car pulses/surges. It's like you are taking your foot on and off the accelerator. I am wondering if something is heating up and expanding just enough to cause a boost leak. MAF?

Another symptom I just noticed. When it starts pulsing there is lots of white smoke. It did not smoke like this before and only smoke when it starts acting up after it reached operating temp. Any ideas?

Leaky intake manifold gasket? Exhaust leak/Egr leak? As the metal parts expand with heat they have more clearance?

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EGR was deleted by previous owner. Perhaps something is not tight. They must have swapped the manifold to do the delete. I may just take my other manifold/egr and put it on.

A new code has now popped up. So the two codes now are:

2 Faults Found:

00575 - Intake Manifold Pressure
17-10 - Control Difference - Intermittent
00550 - Start of Injection Regulation
17-10 - Control Difference - Intermittent

Don't know much about this code, but perhaps timing belt has slipped a tooth? Still does't explain why it only seems to show up after engine heats up though.