I have a 2007 dodge mega cab 4x4 with a hemi in it. The problem that i'am having is that once the truck warms up it starts losing horse power. It idles fine runs fine drives fine and even comes out of over drive and run fine going down the highway. But once you slam on the gas pedal for extra power or even at take off slam on the gas does great til it hits around 3500-4000 rpm then it starts acting like I'm hitting the rev limiter. If I start off with the truck being cold it does just fine slam on the gas runs up around 5500 rpm and shift and so on but as it warms up it gradually starts getting worse and eventually 3500-4000 rpm is the max. I even noticed that once it warms up that even if i need a little extra power to get over a curb say in 4 low i pretty much have to put it to the floor to make it have enough power to get up the curb. And when its warmed up dont even have emough power to power stall the tires. I've replace the knock sensors crank position sensor. The only codes that are in the comp are two for saying that the cats arent working but thats cause I dont have any

 

What are the codes exactly? You have multiple oxygen sensors, if some of those are bad (the ones that went in front of the converters), that would cause you to have no power. The computer really only listens to the oxygen sensors after warm-up, so that could explain why you have power fine until they kick in.

Also, for future reference:
https://dodgeforum.com/forum/dodge-r...s-section.html

 

the codes a a 420 and a 430 i believe and the comp is saying that the cats arenet working properly which is cause I dont have any at all. No codes for bad o2 sensors or anything else. I was thinking fuel pump cause as it warms up it gradually starts losing its power and in the past I had had that problem and it lead back to a fuel pump.but really not sure

 

A bad Cat will make all kinds of problems! Esp what you are describing.
One question tho why would you use 4Lo to get over a curb?

 

Can you replicate this at a stop by brake-torquing the engine? It would help narrow it down to the engine, and rule out the drive train. Your RPMs won't be exactly the same with brakes on and not moving, so try it cold when you know it works and try it hot when you know it's struggling.

 

To willdike I dont have any cats at all it has a straight pipe back to a flowmaster. And I put it in 4 low cause it was a good size curb and I was backing up on to the curve and over into grass at a park so I wasnt trying to mess up there grass by spinning any cause i have 37 inch mud grapplers and one lil spin will take a pretty good chunk out of there grass

 

to buggsy I agree with you completely on the rpm thing. If the truck is just started I have all the power it should and it will power stall the tires. But as I drive the truck say 10 miles or so it starts losing the power it should have let me say also I live in oklahoma and the temp gets up to triple digits so it dont take long for a vehicle to warm up. So once its warmed up it will only let it run up to around 4000 rpm wether your at a stop or if your driving once it hits that mark after being warmed up its almost like your hitting the rev limiter

 

I asked about the 4LO because its kinda pointless but i see you werent trying to spin any... which is good atleast you know how it works.

No Cats are know to have problems even if there is no check engine

 

has it been known to cause the problem i'm having now

 

Yes because the o2 sensor before the Cat tells what fuel air ratio it should have and the o2 sensors after the Cat complimnets the one before it by saying that after the exhaust gas passes through the Cat and changes the gas from one state to another clean state it helps tell when and how much fuel or air to put back.