1994 e320 running heavy

[lebstyle]

hi all, i am posting again.
I have a 1994 e320, i just changed the mass air flow sensor, spark plugs, wires and boots, and had several codes which i cleared.
the car was running rough, when i reset the codes it started running smooth again, but running very sluggish and gas mileage is terrible.
every day i get the engine light, i check the code reader built in the car, i get code 23 Intake manifold pressure (in base module pressure sensor-) with engine running too high/low.
any ideas?
vac leak?
the car is still running smooth, but i did notice its running a little heavy like it doesnt wanna go.

[Ferdman]

lebstyle, what's the mileage on your 1994 E320 and when was the oxygen sensor replaced last?

[manny]

A little food for thought.......how is yor catalytic converter?
Plugged, partially plugged?

[lebstyle]

the car has around 150, 000 miles. ineer changed the oxygen sensor, but its not giving me any codes. and the converter i never checked.
but te car was pretty swift before this poblem. do you think there might be a vacuum leak somewherE?