16V will not rev past 3000 rpm

[dbenz]

I need help on this problem:

'86 190E 16V w/187k with manual 5-Speed
Have had some problems with loosing power at higher altitude or after driving for 4-5 hours. I never was able to pinpoint the exact problem since it was very intermittent. Now the problem looks like it is here to stay.

It will idle, not great, but it does idle. However, it has no power and will not rev past 3000 rpm even in neutral. It seems like it's just not getting fuel at the higher rpm's. I have replaced the fuel pump and filter, removed the exhaust (it almost acts like the exhaust is blocked), and replaced the ECU. All with no change.

Has anybody ever run into a problem like this?

Thanks for the help -- I need it!

dbenz