1988 chevy c3500 5.7l 350 sm465 4 speed manual
Recently had a miss when vehicle warmed up but fixed it after replacing dist/rotor/ button/ig. coil/pickup coil/wires/spark plugs/IACV/TPS/fuel pump/fuel filter. But hidden under all that is a new or exisiting problem I didn't know about. Truck runs fine cold/ warm and shifts thro all gears and has plenty of power. Just at 60+mph it sounds like it wants to go into OD but doesn't and there is no power then till u let off gas and let it get back down to ~60mph. Please help, thanks.
