having problem with rpms,couldnt get over 30 mph and it would cough andsputter whenever i steped on the gas,changed plugs wires oil,didnt help took it to autozone they checked it and said heated o2 sensor was bad and also a couple misfires and output speed sensor was was bad but that could be a misread due to the o2,so i changed the o2 and now i cant even drive it and it runs very rough no cant step on gas and it wants to stall,would this be due to the output speed sensor or some other sensor,,,thanks

 

Remove the O2 sensor from the exhaust altogether, and see if the truck doesn't run better.

 

pulled o2 sensor back out and runs good not moving,havnt tried to drive it yet

 

^^since he's new...

the purpose of that test is checking for a clogged catalytic converter (common on these trucks) the missing O2 sensor gives the exhaust a small place to go. its not a solution - just a test.

 

Clogged cat due to blown plenum gasket.

 

tried driving it and wont go above 20 mph,and starts losing power and coughing

 

The hole for the O2 sensor isn't that big....... Gut the cat. See if that helps.

 

x2 on that cat. Classic symptom, check out the stickied plenum thread for some interesting reading. lol

 

5.2 1998 Dodge Ram changed cap, rotor, plugs, wires, just no power once it under load even the a/c stops blowing and gutted the cat no luck not sure what to check next hasnt came up with any codes but a misfire in two of the cylinders cahnged the plugs that went away. Any ideas speed sensor, map sensor, tps, any help would be appreciated

 

Check fuel pressure.