[sok]

Recently my car sometimes seems to have issues shifting into 4th but only when I'm not on throttle, sometimes the revs would drop and its on neutral for a good second before jerking and going into 4th and sometimes it wouldn't go into 4th at all and I have to up or downshift to get it into gear again. When I do WOT or just light throttle it would shift just fine or jerks just a little into 4th and downshifting is all good. And it seems to always shift fine on D or DS, so it only happens on M mode shifting from 3rd to 4th. One time it didn't go into 4th and kept trying till it failed and dropped to D with a transmission malfunction error which never happened before.

I've replaced the tranny fluid before but don't really know what else I can do, any advice?