I just bought this truck and have had problems going over 75 miles an hour. It seems that this truck would haul ass down the highway but it seems that it is lagging in power. It has 141000mls. I have done the usual tune up with plugs, wires, distributor and cap. I also changed the oil. I was wondering if any of you have any ideas as to why the power seems low. It has a rebuilt tranny still under warranty so it not that. Any ideas would be great.