Well I think the engine is up to temp. WHen I drive it for a while the radiator and all the hoses get hot. I read that the engine only has to get to 180 degrees for it to be able to go into closed loop and if my thermostat is at 192 degrees than that means that the coolant temp should be getting over 192. Could this really prevent a big loss in performance because it is almost impossible to run my truck in 5th gear on the freeway unlesss I am going down hill. On the freeway I almost always have to keep it in 4th just to hold my speed. What else could I check that would do this. The only thing I can really think of that might do this is the fuel pressure regulator or the cat is clogged. I have changed almost every other part. It sucks having such a slow truck and also spending so much on gas. The parts that I can think of off hand that I have changed are....
K&N air filter, fuel filter, MAF sensor, o2 sensor like year and half ago, fuel pump, thermostat, ect sensor, timing belt (and checked timing), fan clutch, disconnected a/c, belts, spark plugs(checked gaps), spark plug wires,

I know theres more I just cant think of them. Please help me I really dont want to have to sell my truck because I love it but I am getting so sick of it not working right.