I have an 88 F-150 extended cab 4X4 Every since I purchased it a year ago the trans seems to hesitate then slams into gear shifting from overdrive to 3rd when trying to accelerate to pass or maintain speed up a hill. All other shifting is normal. Had one mechanic tell me over the phone he thought trans needed an overhaul due to hardned seals. Tried trans seal softner to no avail. If I pull the shift lever down to 3rd (D) before accelerating I can sometimes get a smooth shift. The rest of the time it literally shakes the whole truck violently when slaming into third. I can't help but feel there may be an electrical or sensor problem. as I have also struggled with a surging problem after start up. Once started engine sometimes surges up and down several times them may idle smoothly and then begin the surging again. Thanks for any suggestions.