Engine Mechanical problem
1991 BMW 318 4 cyl Two Wheel Drive Automatic 150,00 miles

The engine skips at 3500 rpm.

At a rapid increase in HP-
The engine runs well when its warm- however at any given time - at 3500 rpm it skips.

Traveling at any speed below 3500 rpm its ok

Rapid run thre the gears it will hesitate at 3500 rpm
Already changed the plugs-
Tried a new sensor and it functions beter with the old one
Changed the gas filter - already went thru 3 tanks of high test gas.

What should i look for -

Help - its a great car - except this flaw

Ty -Ard

Knowing what is causing the hesitation is crucial. Is it spark or fuel? Swapping the air flow meter or trying another DME would be steps I would take, you state the sensor swap changed it, it may be a wiring issue. These are some possibilities, also looking at spark and fuel wave forms on an oscilloscope could be helpful to determine the root cause.