Misfire under load and lugging, no code showing on scan tool

I took my Vic to the shop to get worked on because it has a misfire but I can\\'t get anything on a scan tool... It only does this when lugging in higher gears with low rpm acceleration...my initial thought was a coil pack but they are all in good working condition as I just replaced them at the end of winter. I was told it could be an intake or vacuum leak. Maybe fuel filter?? Also The front end wanders some and the rear end sways, good ball joints and tie rod ends with brand new goodyears. The mechanic said he took it for a good long drive and couldn\\'t find a misfire the wander in the front end or he wander. he said everything was in good working condition (BS), but yet the check engine light was cleared... I left the shop and didn\\'t even make it 3 miles and i noticed right away that nothing had been changed. I believe he just charged me $167 to clear the check engine light......extremely outraged, somebody plz help!!

What to you seems like a misfire could be the transmission hanging in gear. Sounds like she may be on her way out.