About a year ago I had some engine vibration during acceleration. My mechanic determined the 5.7 hemi was stuck in 4cyl mode. Apparently it drops to a 4 cyl during idle or something like that. I never knew. He said he could not turn the feature off but somehow got it to where it just worked in 8cyl mode. Fast forward to a week ago where I had some work done on it again. It needed a new battery and I think when it sat for a little bit without a battery, it must have reset on something. Because the next morning after I began driving, the engine started vibrating so bad around 40 mph I had to pull over. For some reason, If I cut it off and wait about 15 seconds and re start it, it usually doesnt do it again. But it has done this every morning for about a week.I even wonder if it has to do with the enging being cold. I have not noticed it doing this in the afternoons. My mechanic mentioned there were aftermarket devices that plug into the obd2 connector and stop this from happening. Has anyone ever experienced this problem???