Sooo, I've had this car (2002 sunfire with the base 2.2L OHV engine, 4speed automatic) for two years now, and just recently it has started having problems. For example, when taking off from a stop to 90km/h, it shifts fine into 2nd gear at about 3k rpm and 40km/h, then into 3rd at 3k rpm and 55km/h, but then, as it spend the rest of the climb from 55km/h to 90km/h in third, sometimes the rpm's fluctuate about 500rpm up and down, causing the car to seem like it's struggling. then once i reach 90km/h it shifts into 4th gear. i dont kno0w what could be causing this problem. the only thing ive done with it outside of normal driving is using the shifter (PRND321) to shift it manually through all four gear on occasion, as i find it exhilirating sometimes. Could this be causing it? it's not like the gear is slipping, ive seen that happen on my dad's 1981 Benz 380sl from 1st to 3rd.