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Several months ago I had the P122 with a cel. As it progressed I started experiencing engine surging. At first only 1, 2, maybe 3% as shown on my scan gauge. I lived with for a little while until I had a chance to try and diagnose it some. Some of you might know how much I enjoy diagnosing electrical problems and for any who does not I think I would rather have a root canal done. Any way I had pretty much determined that it was a bad apps sensor. I had a Timbo on the truck and was not completly convinced that it was bad. So I googled "apps/tps sensor and found a boat load on ebay for any where between $12 and $90. They all had the same picture and I ended up buying one for $16 bucks. I did this mainly to test with and see what happened. So I installed it and it worked. Surging gone, and no DTC's. Since I did not really trust the cheap apps that I bought, I went ahead and ordered a new Timbo. Put the new on when got it and every thing is great for about 15 minutes and the surging returned. Kept getting the 122 code intermittently and the surge was approaching 8 and 9% on oddasion. Alternator VAC was about .03, the apps sensor voltage read OK thru the pedal range, nothing jumping around. So I put the el cheapo back in and no surging. But in a couple minutes it throws a P222 code with the CEL on. Cleared the code, started the engine and it is instantly back. I cleared several times but always came back instantly on engine start, but no surging. Idled beautifully. So I left it in and lived with the CEL lit and the code present. While it did not surge it was messing with the idle enough to disengage my E brake at times. That is the only way I could tell that it was still trying to surge. Fast forward to1 month ago while changing my oil I am looking at the ground cable from the passenger side battery to the block. Since I am in there I checked it and when I put a wrench on it the weight of the wrench turned it. So I took it off cleaned it up and reattached nice and tight. Over that past moth I started noticing the E brake is working all the time. So this past weekend I reinstalled the old Timbo apps and all is working as it should. No surging, cleared the 222 code with no return And have not seen the 122 code come back either. So I am assuming that ground is associated with the apps ? I have not tried to figure that part out on wiring diagram. I do appreciate all the advice I get from y'all but knew if I had asked when the problem arose I was not in a position to use the advice for a while and just rode it out till I got lucky Seems that ground did solve my problem. Stupid grounds. Too darn many to keep up with.