Okay I have a 2002 Ford Escape with 134k miles, 3.0 Duratec. It had a rough idle, in the 600 range and revved terribly slow as well as accelerating like a house was tied to ot. If the A/C is on it will stall if you put it in gear, in park with the A/C on it will sit around 4-500.
I changed the upper and lower intake gaskets and it seemed to help it accelerate a little better, but the idle was still bad. I read the codes and it showed Bank 2 Sensor 1 was stuck lean. I tried a new MAF with no effect so I returned it and changed the sensor, I cleared the codes and waited to see if it would throw another code. Still idling rough, it eventually threw the same 02 sensor code as well as a TPS code. I replaced the TPS and it had little effect.
There doesn't seem to be any vacuum leaks I've located, PCV boots are in good shape. There is a hissing but it appears to be coming from the Break Booster, the pedal is a little hard as well. Could a bad booster cause the low idle and sluggish acceleration? Did I make a mistake not leaving the new MAF? I'm pretty stumped, my brother insists the ECU needs replacing. Sorry for the really long post, any help would be appreciated

 

You corrected a problem and did not tell the computer it was repaired.
You can try a "forced reset". That is done by removing the negative cable end from the battery and holding it against the positive cable end for 5-10 minutes. This erases the memory in the vehicle computer. Reinstall the negative cable back on the battery,turn the key on and wait a minute or two before staring the engine. You then start the engine without touching the throttle pedal for another few minutes while it learns the new positions, then after a few minutes take it for a normal drive going different speeds and typical driving. The more you drive it the better it should get.