Engine No Power Below 3000 RPM, Then Normal!

AHF, 110 horsepower, manufactured in 05/2000, 100,000 km.
Heut morgen auf der Autobahn! Bei 180km/h plötzlich ein leichter Ruck! Dann bin ich langsamer geworden und wollte wieder beschleunigen, aber is nix passiert! Erst ab 3000 U/min! Nagelt jetzt unten rum ganz schön! Fährt wie ein Trecker, und ab 3000 U/min gibts wieder Schub! Könnte das der LMM sein? RußI don't want that!

best regards
Micha.

EDIT: Error code 17656. I suspect the timing belt is very loose! It was replaced 15,000 km ago! However, after the first occurrence, I drove another 40 km at full throttle! It seemed to be working fine again at higher RPMs. Could the belt have skipped a tooth and caused this error?

z-man wrote:

EDIT: Error code 17656. Found that the timing belt is very loose! It was replaced 15,000 km ago! However, I drove another 40 km at full throttle after the first occurrence! It seemed to be working fine again at higher RPMs! Could the belt have skipped a tooth and caused this error?

I think it's possible.

But if the "check engine" light seems "very loose" and you then drive another 40 kilometers, you shouldn't be surprised if those 40 kilometers turn out to be the most expensive of your life -> engine damage...

Well, I only checked the timing belt after the 40km! I was on the road, after all! But as I said, it was still running! Even at full speed! It worked normally above 3000 RPM!

best regards
Micha.

EDIT:

Okay, so the timing belt has jumped a tooth! Luckily, only one tooth. Something must have gotten in there, as it's cut about 2mm in one spot! I can't figure out how, since the cover was definitely completely closed! Anyway, what I actually need to know is, from when on did you no longer have to replace the idler pulleys? I read something about that somewhere! Because if I'm already working on it, I might as well replace the idler pulleys too, just in case they develop a problem later! Oh, and where exactly are the timing marks? Especially on the crankshaft? On the camshaft, they're on the hole in the transmission bell housing!

best regards
Sure, here is the translation of the text from German to English:

'Micha'

Normally, there's a slot on the transmission side of the crankshaft, but is that no longer the case with your engine?
You insert a "ruler" into this slot.
I made a thick metal strip out of aluminum, and because of that, she can't move at all.