1999 Dodge 1500 Laramie, 318, 46RE. Since I bought the truck, the cruise control generally maintained its speed on flat surfaces and going downhill, and maintained RPMs while going uphill, losing up to 5 mph. But something I did in Michigan changed that; now, when the truck goes uphill with the cruise control on, the transmission goes into passing gear to maintain the speed. The first time it did so was somewhat alarming; at 70 mph, it cruises at just below 2000 RPM, but it suddenly went up to 4500 RPM, and the red-line is 5000 RPM. Milder upgrades now engage the passing gear up to 3000 RPM, but that's still a lot touchier than it was. Also, with the cruise control off, passing gear engages much sooner than it previously did. While up north, I made several changes to the truck, including: Replaced the upstream oxygen sensor. More details on that in the P0133 thread in the Repairs & Maintenance forum. Mileage didn't improve, probably because passing gear uses more gas. Replaced the top of the air cleaner housing with one from a junkyard (the original was cracked, and I'd put some duct tape on it). Replaced the vacuum lines between the firewall and the intake manifold for the HVAC (I'd plugged the old one after it broke, but it was brittle, and probably cracked elsewhere). Something else is wrong there: now, the fan won't come on in any setting. Changed transmission pan, fluid, filter and gasket. The older filter kit for the 727 works on the 46RE, though it takes a third screw to fasten the filter. At the parts store where I bought it, the Wix kit for the 727 cost half as much as the one that the 46RE calls for. The old filter was darker than the new one, but I didn't see any metal shavings in it, or in the pan. Cleaned off some dirt around the transmission mount, and sprayed some carb cleaner in that general area. Wrapped some of the wires near the transmission with black plastic conduit (I first sprayed a few of them with the carb cleaner). Maybe I actually corrected a problem, but I'd rather it wouldn't be so touchy. On older mechanical units, where the passing gear engages can be adjusted, but this transmission is electronically controlled, and I don't know how, or even if, this setting can be changed.