hesitate to accelerate

[prozor7]

Hi to all,
I have '98 Chrysler Stratus 2.0 DOHC ES (Dodge European model) with 100000KM (60000MP). I’m first owner and car is regularly maintained. Only problem I was having with this car is head gasket at 50000KM. This moment I’m tired of mechanic because they can’t solve problem with car and I spend a lot of money.

Problem is following:
On slow acceleration car hesitate to accelerate (stumbling, pushing at back) only from 1500-2800 RPM (with AC it’s even worse) after 2800RPM everything run smoothly. Spark plugs, cables, fuel filter, injection filters etc all new but it didn’t help. Fuel consumption is normal and there is no error code.
On fast acceleration everything works great. Car run smoothly at 200km/h and fuel consumption is 12 liter at that speed.

Please help me to solve problem I really like this car.

P.S. Can you recommend what interface and software (for PC) to purchase for this car, I decide to maintained car myself

thx
prozor7