ive got a 95 silverado z71 and ever since ive had it it has had tranny problems. i changed the tranny filter and nuthin new. when i put it into drive it doesnt start in 1st and it doesnt shift, but if i put it into 1st then manually shift it into second it eventually shifts and then i have to do the same for third but when i put it into drive it doesnt shift. any ideas as to what i could try or whats wrong?? thanx