Hi i have a 2003 1.6 impreza one day i started driving i couldnt go past 75mph in 5th gear but in 4th it was no prob after about 15 min this all went away and also somedays the idle is very jumpy akso driving when the car is cold its pretty jumpy aswell can anyone help im thinking air flow sensor but maybe not thanks.

 

Have you looked to see if there are any codes stored?

 

There is no warning light on, can you check for without the light on