Hey guys,so my van runs real good and drives fine but my trans only shifts into fourth gear once in a while,usually after i have been driving on the highway for about 10 miles.After it shifts it always shifts after thatve as long as im still driving.If I STOP and shut it off for a while unless its just afew minutes I have to drive for a long while again before it shifts into fourth.But yesterday i drove over 20 miles in 3rd and it never shifted into 4th.I m getting sick of this problem!