I have a 97 Dodge Ram 2500 gas 360 5.9L.
I attached a code reader to the dodge and it gives me different cylinder misfires every time. It started with 1,2,3 then it was just 1,2 now it's 3,6 and it's telling me the throttle position sensor switch/ high circuit. The dodge backfires a lot and barely moves. It struggles to make it to 40 mph. The truck feels bogged down and idles rough. The rpms at idle stay around 1. The code reader also gave me live data and said the cat and the 02 sensor weren't working, if I replace both the cat and the 02 sensor will it fix my problem?? Please help

 

Replacing the TPS, cat, and oxygen sensor might solve the problem, but if the cat's fouled (as your description of the symptoms imply that it might be) you might also have a cracked head which usually manifests as cracks between the valve seats of the #8 cylinder caused by overheating.

Now: What usually takes out oxygen sensors and catalytic converters that haven't simply died of old age is loss of oil control, most commonly a leaking intake manifold plenum pan gasket. There's a sticky topic in this forum "End-all Be-all plenum thread" that you'll want to look at carefully. If that gasket's shot, you'll want to fix it so it can't kill the other new parts you're about to install.

 

I checked the plenum gasket and it wasn't that, nor do I have a clogged cat or bad oxygen sensor, just replaced the tps sensor no change in the truck

 

I'm with UnregistereUser, your cat is most likely clogged. Get it pressure tested before replacing any sensors.

 

Remove the front O2 sensor from the exhaust, go for a drive, see if it runs better.

 

This is great advice, I actually did that this morning.

I had random misfires, the dreaded blinking CEL, and the truck was more boggy than I could believe. Pulling the front oxygen sensor got me 100 miles to my exhaust shop. It ran much, much better on the drive up there--particularly uphill--but it was loud AF: my wife's dog was afraid to get in the truck!

This is the second catalytic converter I've had put on the truck (218,000 miles). The first replacement went on about 50,000 miles ago; heads were replaced about 25,000 miles ago, along with 1.7 roller rockers. At the time of the head replacement I also added a 52mm Fastman throttle body and Gibson headers. With those parts, and with the K&N Filter and SCT Hemifever tuner and the dual (cat-back) exhaust I am wondering with more airflow will I be replacing catalysts every other year or so.

For what it's worth, my exhaust guy said he didn't want to use a Magnaflow on it as he said the quality of their products was declining.

 

Have you ever fixed your plenum? Burning oil that is sucked in thru the blown gasket will smoke your cat in short order.

 

Plenum pan was replaced about 100,000 miles ago with the Hughes plate kit. Low oil consumption and no pinging since then.

It was pulled at the time of cylinder head replacement, but I peeked in through the throttle body last weekend and was truly startled by how shiny it still was.

I'm think I'm going to stay away from fuel additives / injector cleaners from here on out. I was running high octane at the time that the cat bit the dust, and struggling to maintain 65mph uphill.

Come to think of it, that was the exact situation when I lost the original cat, right down to adding a can of injector cleaner before a 300 mile highway trip...

 

Additives shouldn't matter..... If you don't have emissions testing, just delete the cat, and call it a day.

 

Does he have any info to back his claim? I have the direct fit magnaflow and it has been great for the 4 years it has been in. Never heard anything bad about them.