I added this info to a thread I found in the technical forum, but thought I would post it here as well.

I have a 96 Magnum 425 4×4 doing same thing. Just bought it, ran fine…wide open was no problem. However the drive line was a mess. I changed sprockets and chains, few barrings and seals. Only thing I have to motor wise is new air filter, Plug and fuel lines. Well when I put it back together now from mid to full throttle it bogg’s out and back fires. New gas and I made sure no water, ran it till the carb went dry, then turned gas back on and it’s pulling fuel fine, and does same thing. Put old plug back in, checked the ETC and stuff, did the "Black wire Pull" test… everything I could think of. What could have happen in the 3 weeks I had it apart. Would the cam go bad that fast, just sitting. FYI it does this in neutral or drive with or without the over-ride. I am totally at my wits end… HELP!!!!!!!!!!!!!!!!!!!