i own a 93 s10 blazer 4.3 cpi 4l60e trans has 280000 miles when cold trans will not shift out of 1st till i reach high rpm then slams into 2nd when warn does not do it as bad not sure on exact rpm does not have tach changed tranny fluid and filter added a bottle of lucas did not find excessive metal in pan and fluid was a little burned not bad seen worse cant figure it out and trans parts are to expensive to guess please help it will be appreciated