1997 Dodge Ram 5.9 Sport.

When I run down I95 at 70+ mph my truck starts to miss fire and my RPM gauge goes all over the place until I back off the gas, then it'll start back up when I get up to speed.

It doesn't violently lunge but it's pretty damn noticeable. I checked the plugs and they're fine. I've replaced the CAM position sensor twice before (last time was 3+ years ago) but both of those times it was because the truck would just die when the engine got hot, this is different. I hope it's not transmission related

I'm just looking on things to check myself before I bring it somewhere, I'm going to try to get a video of what it does today and post it so the problem is more clear.

Any suggestions and help would be appreciated, thanks!

 

Crank sensor? Clogging cat? Fuel pressure? How old is the dist cap?

 

I'm sure my cat is pretty clogged, I just pulled the pre-cat O2 sensor and it sounds like a banshee going down the street. I'm getting ready to take a few days off work and do the plenum so I should probably do the cat at the same time.

Anyone happen to know the easiest way to swap a cat converter with a sawz-all and no lift?

 

If your truck is 4x4, shouldn't be too bad.... if it isn't, jack up the front, and then support it on jack stands. (don't trust the jack, and I personally won't use ramps...... had a bad experience with them at one point.)

On yours though, you have two pipes going into the cat, and one coming out. I think some welding is going to pretty much be required, unless you pick up a direct-fit replacement, or a Jegs or Summit Off-Road Y-pipe....

When you do the plenum, replace the pre-cat O2 sensor as well. No easier time to get to the distributor cap either.

 

I will probably do this soon enough and be back with more questions, when I replace the cat I'll definitely go direct-fit because my welding isn't up to snuff. Thanks for the info!

 

Make sure the plenum is good before replacing the cat. Otherwise, you will end up replacing it again.....