Help! 560SL loses power above 4000 RPM's
I bought my 88 560SL last October and have replaced most of the usual suspects for a car with 120K miles on it.
* both fuel pumps and filter
* Spark plugs, wires, dist. cap, rotor, coil, air filter
* timing chain, rail's and tensioner
* O2 sensor
* Sub frame/motor mounts/flex disk
* Fuel injector seals
The car starts every time on the first crank and idles fairly smooth and steady at about 650 RPM's in gear, and 750 RPM's in neutral.
The engine runs smooth and strong up to about 4000 RPM's where it just seems to run out of power. It will pull to 6000 RPM red-line but with reduced power. It feels like the fuel flow is reduced or that the timing has been retarded and at the same time the engine takes on a different sound. Not any strange noise, but a change in frequency. This problem only happens between 4000 and 6000 RPM.
Could this be a blocked Cat??? Bad injector??? I am running out of ideas.
Help!! any input is greatly appreciated....