[4boostin]

2004 Buick Rainier with the 4.2 has 170K on it. Bought it with 140K and it's been pretty much trouble free. New spark plugs a year ago. I started getting the P0171 and P0172 several months ago. They would only show up while driving up and down a steep canyon every once and a while. Now they are coming on a few times a week along with the P0106 during normal driving. It has been running smoothly but seems less powerful. (It's the wifes car, so I don't drive it too often) After pulling the FP relay to de-pressurize the line, I connected a fuel pressure gauge. FP was at about 50-55 psi, and didn't drop after sitting 20 minutes. Taped the gauge to the drivers window and went for a drive and it stayed steady at 55 psi under full throttle. I pulled the relay again to remove line pressure and disconnected the gauge. When I restarted the car it was missing badly at idle. Took it for a drive and it ran like a slug...still missing badly and gave a P0171 code. The FP filter looked old and rusty so I changed it. With the new fuel filter, fuel pressure is now at 60lbs, but it is still missing badly. Runs like it's only on 5 cylinders, and is giving a P0300. When I disconnect the vacuum line from the FP regulator with the engine running, the FP does not change, and there seems to be little or no vacuum coming from where the vacuum line connects to the intake when I put my finger on it. I'm wondering if my FP regulator is bad, or if and injector got plugged during the process. ???