I have a 1990 Chevy K1500. I've noticed the last several times I towed, the old gal seemed WAY under powered. So I change ignition coil, plugs, wires, distributor cap and rotor. This helped with the "around town" driving, but did nothing for the lack of power with towing. While driving along (not in tow) the motor just completley bogged down. If I floor it, the motor bogs down even more. When the truck is in park, the motor runs and idles perfectly.... No bogging down what so ever, but put it in gear and now it bogs again. The truck has no power and literally can only go 5MPH. Heres the funny part. After truck cools, it drives great for 1st mile, then goes back into bog down mode. Any input would be greatly appreciated. Thanks.