I have a 99 dodge ram ext cab 5.9 4X4. just bought it. ran great took it on a trip even but the other day i was getting parts for my other truck and when i came out there was nothing,i found loose battery terminals and tightend them. Then it would start and die instantly when gas released after a minute it stayed running and i made it home fine but sounded funny . took it out again that night and on way home it wouldnt go over 40 mph, then checked trans and a few things and tryed again and wouldnt go over 25 then 5 now nothing just turns over fires once in a while but not start. In the end when it would start it was real rough like only 4 or 5 cylinders or something. i changed plugs rotor cap wires went through all fluids air filter fuel pressure is good 45psi and verified spark also no codes on the obd2 any help would be appreciated

 

I think the cat is clogged, unscrew the precat o2 sensor and see how it runs.

 

^^^second this....if not check fuel pressure at rail

 

think you got it pulled sensor and it started put it in and didnt thanks alot you just saved me a ton of unneeded work gonna get a new cat this week and hopefully im good to go thanks again

 

You are going to want to fix your plenum then. That's why the cat went bad.

 

Hate to be the bearer of bad news but the heads most likely cracked from the extreme heat and pressure of clogged cat

 

since when does a dodge head not have cracks...pretty sure that was part of the selling point

 

when i pulled the sensor it ran as good as id expect from a 3/4 in hole and idled. today due to the fact that i needed to be able to move it. i gutted the cat and welded it back up sounds great and stronger than ever but wont idle now could this be because of the lack of back pressure from the cat or should i start trouble shooting again

 

Disconnect the battery, take off the throttle body, (get a new gasket first, they are like two bucks.....), take off the IAC motor (on the back of the throttle body), and CLEAN everything really well. Do not move the pintle in the IAC motor, just clean the thing off.

Reassemble with the new gasket, and start the truck. It may not want to idle on its own right away, but, it should figger it out in pretty short order.

If that doesn't help, replace the IAC motor.