RPM's bouncing, Wont Shift, Engine bogs down
 

Hello guys,

2002 Dak, 3.9L 4x4, automatic. 42,000 kms (I know, barely driven).

Just picked up it tonight, driving back from where I got it and all of a sudden on the highway the RPM's began bouncing from 2000 to 2500 and the truck was jerking slightly. This was going 100 km/h (60mph).

When I got off the highway, the transmission would refuse to shift gears. I was nearing 3500-4000 RPM in first gear while trying to shift and then out of no where it would shift hard!

I've replaced the plugs, wires, filters and gas cap... $600 later and it's still happening. I'm sure its not the transmission... it drove fine till I got to the highway and when I got off I shut the engine off, waited 10 mins and it drove fine home. Took it out for a spin in the city shortly after and it happened again. I also stopped by a friend who has a scanner and he scanned it and it was throwing 4 codes:

P0300
P0303
P0304
P0455

I haven't researched these codes yet but if they sound familiar please add in any info.

Thanks!

I don't think yo have transmission problem. Looks like you have a misfire prblem. Have you done a compression test?

I think so... I just bought this truck last night.

Its been to the dealer 3 times for this problem, first time they said nothing was wrong, second time they replaced plugs + wires, third time they said there was a leak in the gas cap and put in a new one. I drove it this morning and it was fine but I'm positive its going to happen again.

About the transmissions... Do they shift hard in these trucks? I have a Grand Prix with 230,000 kms on it and the tranny is almost done, but the truck feels like it shifts just as hard with only 42,000 kms on it.

Maybe Im just used to driving a car with a smooth transmission and haven't quite gotten the feel for this truck yet.

Thanks

mine do something similar but only when start it was a bad oxygen sensor well a shortcut in one but as i said it was only when start and mine is manual so dont know about the shift thing