Joe, the TPS on the W210 is a pretty stable unit (unlike the PPS on the S class...) but they can fail.

The classic code is P0120 (not Po120), though if your code reader isn't finding a code, even a pending one (some won't read pending codes) then you may not have a TPS issue. That said, I can recall reading at least one instance in which the TPS was bad but didn't trigger a code.

Try this first: run the throttle/transmissions adaptations reset. It won't hurt anything (just restores default shift settings against the range of the TPS motion) and if it works for a while and then comes back, that will pretty much confirm that it's the TPS...code or not.

And unlike our friend on the dark continent, they are not very expensive here (Peach Parts sells the MB part for $215 and some unspecified ones for $130 and $150; ********az has the Hella brand for $124, and I would certainly trust Hella). Whatever the cost, however, like him, it's an easy ten-minute job to change. Fiddling with the spring is the hardest part.

So to sum up: run the throttle/transmission adaptation reset and drive normally for a day or two, then try the WOT thing. If it doesn't come back, it was a transient hitch in your giddy-up. If it returns, code or no, I would replace the TPS. Your part number is 012-542-33-17.

Good luck.