Acceleration problem

[christopher.witbooi]

Hi. I’m new to the forum, this is my first post. Please bear with me.
I have a 2007 2.0R legacy :smt007 . The problem started a month ago after a service, at a Subaru dealer. When the revs climb to 2000rpm and up toward 3000rpm the car is very sluggish and almost hesitates to accelerate, from 4000rpm all good again. When I disconnect the battery for a couple of mins, then reconnect the problems goes away for a day or so.
The car has been to Subaru three times already, today I took the car to the dealer I bought it from to be looked at again. Luckily I have a warranty in place; unfortunately the courtesy car is a Toyota hatchback (sucks ASS :smt015 )
Can anyone give me some probable causes please?

regards
chris

[harrymaneuvers]

Could be plug wires, coil pack, TPS, IACV, knock sensor, O2 sensor or possible MAF.

[christopher.witbooi]

Could be plug wires, coil pack, TPS, IACV, knock sensor, O2 sensor or possible MAF.

its been almost 3 weeks since i booked my car in to be looked at again. i suggested the above mentioned items, and with the policy of the customer always being right, the technician only upgraded the soft wear of the cpu. car worked great for a week, then same problem. slightly at first but then to the extend i struggled to get the car home. i had to go work the next day but booked the car for the monday morning. low and behold problem gone. by shear luck discoverd if i let the car idle until the revs drop entirely, not only is the problem of gone but the gear changes are smoother also. now i am really confused. also discoverd at the last service the spark plugs was not changed, only checked fluid levels. could this be an issue

once again thank you