Have 99 dodge diesel that I have been fighting lockup issues forever (450k mi) finally fixed with $20 noise limiter on the APPS wire to the computer. Now a few months later I am having trouble with the voltage dropping then surging or going to lymph mode idle while in cruise control only. No problems when using foot throttle only. I measured the voltage where the wire comes out of the APPS with a volt meter while driving. Idle voltage is .41 volts. 55 MPH averages about .9 volts on flat ground. I had no voltage issues, measured the same way, when dealing with the lockup issues. I did do all the other lock up fixes be fore the noise limiter fixed it. There was, however, more of a lock up issue during warm weather and slightly lower system voltage due to air cond on etc. I think something is wrong with Speed Control. Don't know what is causing the voltage drop. Any ideas. PS. getting 121 and 122 codes if it goes to lymph idle. It was also missing and surging a bit at idle or decelerating just prior to the present issue, Also, since fixing the lockup issue it wont down shift to third for passing gear. Let me know.