Why does it miss when accelerating?

We have replaced everything electrical under the hood to include, the rotater button pickup coil, wires, plugs, ignition coil. TPI, the airflow sensor, egr, egr modulater. Just about everything you can replace. Somedays it doesn't do it at all. It seems to be worse with the overdrive turned off. Iff you get the accelarater in a certain spot it runs good. But when your accellarating if you don't push the pedal all the way to the floor it takes for ever to build speed. When your going down the road to go faster you have to push the gas down untill it makes the transmission shift into a lower gear before it will take off. And it shifts really fast also. Its like the truck is in the wrong gear for the rpms its doing.

Ok will do. Thank you very much. No one has suggested anything other than replacing parts in the ignition and fuel components till now.I had a thought that it might be something else but dont really know much about this vehicle. This is a great source of information it's nice to be able to ask questions without being charged $60 or more an hour. I will definately try to donate some money to this site as soon as I recover from all I have spent on this vehicle. Again thank you very much.

Im sorry I was so excited I answered before I told my husband what you said. He said the cat converter was removed and new exhaust put on.I am starting to feel so defeated with this vehicle. I still think this is a great source of info and will donate some money as soon as I can thank you.

Yes the converter was replaced with a new one. The thing ran great untill the starter went out. After it was replaced the tpi went out. It was replaced and ran great for about three days then it started missing. All these parts were replaced at the recomendation of a mechanic. For some reason it won't show any codes when it's hooked up to a diagnostic tool. I have even tried to use the diag, port under the hood by using the jump wire on the connectors like my repair manual says. The engine light works so thats not the problem with that. It's been suggested that the torqe comverter could be the problem since when you accelerate it doesnt build any rpms very fast. It only takes off when you give it enough gas to shift into a lower gear. Then it reves up real high and shifts back out really quick. But once it gets up to speed and you let off the accelarater to hold it at 55 it starts to slow down and you have to do it all over again. There are not many parts left to replace that dont require tearing down the engine. About the only thing that hasn't been replaced is the ecm.

Yes as I said it was checked by a mechanic who could find nothing wrong with the engine. It has been to three different shops and none can find anything wrong with it. No reason why it wont show codes but it wont. Your reply seems a bit condecending in tone, I am not a idiot, component testing is usualy the way to go when you cant use diagnostic equipment. I thought maybe there would be something the four of us had overlooked and with this being something tha tmight have happened to someone else I might get a quick answer. But apparently that is not the case. Thank you for your time.

They were not replaced but were checked for voltage and were fine and have had a cleaner ran through them.