need some help here, 2001 165k miles just did UVCH both sides, shop did the job for me as I was out of town at time. Did inside wiring harnesses as well, when picked truck up it ran awsome pulled hard and sounded good, ran like this for the 20 min drive home, next morning 10*f and as soon as it went to high idle I head a snap and then it started running rough, rpm wont stay steady and and seems like it is running on 6 or 7 cylinders, it used to jump up to 1200 or 1300 rpm in high idle and now it just goes above 1000. I had to drive to work so then when I get rolling it feels like its being muffled and then it will jump rpm by 100 to 200 rpm and pull normal and hard then cut back again, when up to speed it feels like its being muffled and lack of power but seems to run smooth. Pulled the EBPV connector at pedistal and no change. Oil is good and fresh, air filter is good and fuel filter has approx. 1200 miles on it. Took it back to shop and no codes at all. buzz test sounded good but still #8 contribution coming up but that has come up for 3 yrs since replacing CPS. Reason for changing UVCH was to be sure no problems showed up with glow plugs and to make sure that wasnt the problem with #8, truck is going to see -35 to -40 this winter. Any ideas here? ph ya and when it changes rpm and seems like it cuts in and out it is abrupt it changes bang right now!