Ive been doing a little research about this problem I am having. On my way home from work the other day my 96 impreza 2.2 started to be sluggish. It doesnt seem as if the engine itself is the culprit, more along the air fuel mixture coming in. I have recently replaced head gaskets, upstream 02 sensor, as well as plugs and wires. The car doesnt have any problems revving, but as soon as power is put to the wheels you can feel it not pushing as hard as it should. Any other suggestions on what could be leading to the hesitation it has?

Does the engine rev up while its in gear? but the car doesn't go any faster?

Or are you saying you can rev it fine when its in nuetral?

 

Is it a manual or auto trans?