Reposting; attempt from 15 minutes ago has not appeared.
Plain 6-cyl engine (i.e., not SHO). 85K miles. Works OK in R and in 1st. In D or in OD it moves out OK, but when it should shift to next gear it freewheels. If it slows enough it downshifts in 1st(?). Fluid level is OK and fluid looks OK.
Is that enough to diagnose the problem and guess a cost, or should I just take it to a mechanic. Is “regular” mechanic OK, or should I look for a transmission specialist.
Again, sorry if this is a duplicate post.