I own a 2000 OBW 2.5L manual with 115k on it. Just bought it and performed a full tune up which helped it run much better. I noticed a bit of a hesatation/stumble around 2250 rpm. Mostly in 3rd but also in 2nd and a little in 4th. This happens during accleration most of the time but sometimes not at all. I can live with it but would like to fix it because it leads to jerky shifting. Any ideas?