I have a 96 Ram 1500 5.2 4x4. When I am driving down the road and hit the gas sometimes ussually when I barely touch it the truck wants to hesitate and like skip a couple times then go. Then when I put it in reverse and barely hit gas the rpm's will go down to like 300 then come back up. My wife was driving it the other day and when she put it in reverse it died, but started right back up. I thought it needed a tune up because it's showing a misfire code. So I changed the plugs, wires, dist. cap, and rotor button but it still does the same thing ?

 

Possible TPS, or failing O2 sensor. Does it do it after it has ran a few minutes? Or, all the time??

 

could also be a vacuum leak. you can prove/dis-prove it by temporarily disconnecting all vac lines at the manifold and plugging them off. beware you may not have power brakes and/or in older vehicles - auto trans shift.

 

It seems to only do it once the engine is warm. I thought maybe clogged cat, but was unsure ?

 

Could definitely be a bad coil pack.

 

Tap on the Cat with a hammer if you hear anything rattling inside. Then it is time to replace it. I just went through the same thing spent tons of money on sensors that were good.

 

Like dhvaughan suggested, after warm up could also indicate worn out O2 sensor (pre-catalytic converter), as the PCM pretty much ignores those until its warmed up.

 

Does the hi flow cat help with mpg and stuff and what will it make my flowmasters sound like ? How do you know if the precat O2 sensor is bad ?

 

How many miles on the truck, and are the sensors original?

 

125k not sure if they are original I bought it with 117k almost a year ago.