I was driving home today after washing my truck. I was going a steady 55mph. the truck just started cycling in and out of torque converter lock up. I was holding a constant speed on a flat surface. It also seemed a bit delayed going into overdrive when accelerating. When I got home, the idle was very unsteady. It would go up to like 1500 rpm, then almost die at 400. Vacuum reads about 17 inches( I live a mile above sea level) and goes down to 10 when the Idle drops low. I disconnected the tps even replaced it with no change in behavior. How do you test the tps circuit? What else could cause my truck to do this?