My 4runner rolls backwards while in D on semi-steep inclines. It also barely creeps forward in D with no throttle input. Would that be low trans fluid? I think the idle is slightly low too. A while ago I changed the trans fluid (stripped the drain plug so have been very careful about putting too much in because the drain wont come out), cleaned the throttle body, cleaned the IAC, replaced throttle body and IAC gaskets, cleaned MAF and messed around with the throttle cable adjuster. It started after I did all that stuff and doesn't seem as peppy as before.