You gotta see this ......

I think adding adjustable rockers to a Mopar is almost imperative. I know lots of people run the stock ones. Adding adjustable rockers does several good things. One of the most important to me is getting the lifter preload right with hydraulic lifters and with adjustable rockers, you can do that and it does make a difference.

It may or may not have solved the OP's problem, but it is a good upgrade, nonetheless, IMO.