If you lurk around on here many of you know I had an issue with my pickup about a month ago. Well I thought I had fixed it and did, to an extent. The original issue was power loss and hesitation. I finally got that somewhat corrected I figured out that due to having a throttle body spacer, "salad bowl" and injector spacer that my engine was running lean. First I tested fuel pressure was about 11-12 psi, bumped it up because I have an adjustable fuel pressure regulator. I didn't want to hook the pressure gauge back up so I just bumped it up a little bit and put it all back together to test. It improved power but I still wasn't satisfied so I then advanced the base timing to about 4 degrees. Tested again and it ran great. Drove it a couple days and it was like driving a totally different pickup. But one day I was driving it check engine light came on. Checked the code and it was code 42- ignition bypass circuit error and 44- left bank o2 sensor, lean condition indicated. Inspected my timing advance wire and all other ignition related wiring everything checked out, so I then unhooked the battery to clear codes and hooked it back up. Drove a while to make sure code didn't come back and it didn't. Then my problem started. It still runs good but not as good as it did before unhooking the battery. It idles pretty low in the rpm range, idling the engine shakes like when you shut off a diesel and sounds like an engine with a cam that lopes, in other words the idle isn't very smooth. But it is only not smooth once it's warmed up. When it's cold and is in high idle to reach operating temp, it's nice and smooth. Not only that but the exhaust smells very very strong(I don't have a cat on it but it's still way strong) so strong that you can smell it from inside a building if you are parallel parked next to it. It also is getting unbelievably bad fuel mileage. On a 15 mile drive this morning it went from a little under half a tank to a little over a 1/4 of a tank and it's a 30 gal tank. So what should I even start with to correct this problem? I know I didn't bump the fuel pressure up more than a couple psi, but I will get an actual reading of it tonight when I get home. The reason I don't know where to start though is, my truck runs good still now(not as good as it dud when I first made the changes but still better than it originally did) it still has decent amount of power. I even pulled a few plugs and checked and they are a nice burnt chocolate color so it shouldn't be rich. Something has to be causing those issues though. Timing maybe? I have no idea. Help please.