So here is the deal, I have 2002 Dodge Ram 5.9L Quad SLT 4X4 and its seems I am having suspension issues. Now, its not the tires or the alignment, I just got new Cooper Discoverers thrown on there today with and alignment.
The issue that I am having is when Im driving over 40mph at around 1k-1500 rpm with my foot on the gas, there is this weird jerkin/shaking that goes on. Once i hit 2k rpm its fine or if I am coasting at what ever speed. Now, when Im at highway speeds around the same rpm, it is doing the same thing, but worse, as if my car is about to fall apart. I doubt its engine issues because when the car is in neutral/ parked I rev it up to that same rpm and nothing. However, my check engine light is on and I have code P301. Now I do not know if this is related or not but I know I am losing mpgs here. Someone told me (mechanic) that it may be my rear diff. pinion seals. I took it to the dealer and the service assoc. (ignorant) Told me that i need new tires and alignment(before i had gotten it done of course) and I had explained to him what a "mechanic" had told me about the pinion seal and that he was sure that it wasnt that, that it was a 4 tires new alignment problem.
So my fellow rammers, as much as I love my truck I hate dealing with unresolvable problems. Please help, i would greatly appreciate it any info/advice you can give me.

 

I don't find a "P301" code, but "P0301" indicates a cylinder 1 misfire. Take a look at your plug wires/connections. As for the vibration, did they balance the tires when they mounted them?

 

Sorry I forgot to mention (if it matters) that its a 1500 and its GAS not Diesel. Also, I recently changed the spark plugs(with oem not after market) as well as properly gapped. I also replaced the spark plug wires and coils with oem and the distributor cap and rotor. This was done about 3-4 months ago. and I just recently got P301 engine light code.

 

Sorry thats what I meant P0301. Yes the tires were properly balanced before mounting. This vibration/jerking has been going on for 10 days and I just got the tires mounted and balanced along with alignment today.

 

change the plugs and wires, stay away from that dealer, they gave you bad info once they will do it again!!

Also nest time it is doing that shaking try turning your overdrive off and see if that stops it. Quite often the transmission will get confused and be jumping in and out of overdrive and cause a shaking sensation

 

Thanks SMKNRAM, ill try that next time with the O/D. I recently replaced my plugs and wires along with the dist. cap and rotor, all with OEM parts, even properly gaping the spark plugs.