89 245 auto with 338k on it. second owner, i'm assuming original transmission. only shop done work on tranny was in 2002 (135K) when rear ujoint in driveshft replaced and trans filter cleaned and kickdown cable replaced and adjusted.all good after that. at 218k in 2005 trans rear seal, bushing and tail shaft housing gasket replaced. after that and up to now just yearly trans fluid flush.

this winter after 200 mile day of steep up and downs on 200 mile drive, the tranny acted up. very long shift from 1st to 2nd ( half mile or so.)then strange vague shifts there after ie 3 gear shifts in 100 yds then rev in 3rd to 4th. mushiness in shifts was main symptom. did trans flush and it helped bit but few more drives up steep hills worsened whatever problem it has. now, when cold , it will shift 1-4 for 5 miles and onto highway ( 65mph limit). if i put foot into gas pedal just tiniest bit it will drop out 4th and into 3rd.and keep doing that till i get off highway and then it won't get out of 2nd on city streets. seems to be slipping before it makes that 4th to 3rd drop. accelerates great in 3rd then goes into 4th if i let off gas but then back to the drop into 3rd nonsense when i just touch gas pedal.

any thoughts on this? am i looking at tranny change out? they don't last forever i know. what inspections ( car on stands in driveway) can i do to confirm problems? summer and all it's light has finally gotten to anchorage so working in driveway a comfortable proposition as opposed to few months ago.

thanks
gary c.