My 99 Dakota with the 5.2 has gotten really sluggish over time and I'm not sure why.

It's slowly gotten worse. Now it's at the point where I have to fight it to maintain 65-70 MPH on the highway and my 0-60 time was 27 seconds. Everything runs smoothly, it starts fine, etc...

The engine does OK between 1000-2000 RPM, but it really struggles to get much over 3000 RPM if I'm accelerating up hill or even into a good headwind. There is just NO top end power. And even in town getting up to 45 MPH means flooring it and waiting for it to slowly build speed. It basically just feels like it's missing about 1/2 of it's horsepower.

I have a few ideas but don't want to just throw parts at it.

I'm thinking it could be a clogged fuel filter. The lack of power at high RPM would fit. But I've read that replacing the fuel filter means replacing the whole fuel pump assemble (removing the bed of the truck).

Another idea would be a really clogged cat. But I had a CEL for a bad O2 sensor about a month back so I replaced both O2 sensors and it hasn't thrown any codes since. I'm thinking it would throw a code if the cat was that clogged.

I've also read that these engines have a known issue with the plenum gasket that can cause similar symptoms, but I'm not burning any oil and again... I don't really want to just throw parts at it.

Any Ideas?

 

When's the last time you replaced the plugs, cap, rotor, air filter, etc?

Sometimes a bad MAP sensor can cause these problems. It may/may not throw a code.

 

ON the Cat; not always 100% true.. my cat blew out (because of bad fuel and coil burnt up and on startup when i got her running all the gas went boom in there.. anyways he O2 Sensor never triggered a CEL.. I can take the Cat off and it wont trip a CEL light.. so just saying..

and 27 Seconds 0-60? My 97 318 4x4 CC was doing between 10-11 seconds. And that's with Duratracs. (ANd I got the vid to prove it too )

 

Read this will tell all you need to know about the plenum
https://dodgeforum.com/forum/2nd-gen-ram-tech/286307-end-all-be-all-plenum-thread.html

0-60 with my v6 is 11.465.

 

I went ahead and cut the cat off today with the sawzall and it was just a jumbled mess of honeycomb in there. I took a quick run down the highway with the cat cut off (exhaust just dumping out at the firewall) and ran a 15.63 sec 0-60. Which is more like it for a lifted Dakota on 33" mud tires.

I just patched the exhaust up with some 2 1/2" pipe until the new high flow cat gets here in the mail. It ran a 15.87 sec 1/4 mile with that setup.

And I definitely got my top end power back. It's no race car, but I actually have more power above 1800 RPM than below now.

 

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