So, I have a 94 dakota, 5.2l 4wd and it lost its ***** somewhere. I was trying to drive it yesterday on the interstate and it just wouldn't go. When it down shifted for a hill or something, the rpm would go up and my speed did the opposite. eventually it just got worse but was able to nurse it back to my house. All my fluids seem alright. No check engine light, no codes. There was a sucking noise that was real bad and found a vacuum leak, but not really the problem. Also it idles at about 400 rpm right now when it used to be around 1000. Any ideas?

 

Plenum shot. Clogged catalytic converter.

 

I'd check the plenum, and check for cat blockage, as JKeaton suggested.

RwP

 

My '94 started losing power. I changed the cat converter and it made a huge difference. Did the same on my '96. Same results. Ray

 

And if you don't fix your plenum, you will be replacing them again.....

 

I am not a mechanic. Could you explain your remark?

 

He is referring to the intake plenum. The intake is the half barrel shaped part that the throttle body is on top of. You may have mistaken the Throttle Body for the carburetor.

Anyway the intake has a flat plate sealing the bottom of it. Dodge chose to make that plate out of stamped steel. The Intake is made of Aluminum. This means they expand and contract at different rates which destroys the gasket between them and lets oil into the intake. Over time this oil being burned ruins the Catalytic converter.
You can just replace the gasket but then you will have to again down the road. Or you can do the repair which is to get a kit that has an aluminum plenum plate to install in place of the OE plenum. I got a Hughes Engines kit because that is what I found when researching problems similar to your here. There are other companies that make kits.
The way to see if you need it is to look into the Throttle Body to see if the flap (butterfly) is not oily look inside for oil puddles or deposits. If there is oil the gasket is shot.

If you do the kit or just the gasket there are several things you should also change since you will have removed a lot of parts just to get at the intake. I replaced the sensors in the front near the thermostat, the thermostat, the short elbow hose that fits back there. You might want to add in a timing chain tensioner and a new timing chain and a new water pump.

 

What he said above. Explained it perfectly.

 

Well ya'll were on the right track. My cat was very clogged. My gasket between the air filter and throttle body was busted. I cleaned the **** out of it and replaced all the gaskets, along with some cracked vacuum lines and was able to get vacuum back in the intake again. Now that they are both fixed, it purrs again thank god. Thanks for the tips

 

Awesome! Love it when people have positive results from the suggestions offered in the forum.