2001 Dodge ram missing and running bad

The first n most simple is to take the beast to an exhaust shop n have them check it for a clogged cat...they usually do this for free.

I have had the catalytic converter removed I replace the map sensor the throttle positioning sensor the air idle control sensor the pickup coil the crankshaft sensor the fuel pump on the only thing that I have not replaced is the coolant temp sensor in the intake temp sensor I also replaced the pre cat O2 sensor

Blaming the cat is like watching a '70's cop or PI show, 9 times outta 10, the bad guy's name will be Stryker AND he'll be of Italian heritage even if he's a cop...go figgur...so you save time n go there first. Doesn't mean the cat couldn't have gone bad again or even the muffler has come apart on the inside, try revving the engine n listening to the exhaust pipe n see if it gives out an asthmatic hiss or a throaty grunt. Or, try removing the upstream O2 sensor from the exhaust n see if the engine runs any better. It'll set off a money light n it'll be loud...but very informative! Also, remove the oil filler cap from the valve cover with the engine running n listen for a hissing noise. That is a shore sine of a leaky/busted intake gasket. I understand that right now, you're looking for simple/obvious answers n since we're diagnosing from a distance, you go after the common failures first...ya know?