Symptoms and background on issues. I don't know if they're related or not.

1. Rough Idle. Installed ARD Green Tune, car ran great for a year. A few weeks ago, on morning start ups, RPM goes to 1500, then drops to 500ish, sounds like its going to stall, but pulls it out to 800. Saw a corresponding dimming in the dash lights with the rev drop today. It has started to do this at redlights now too.

2. Engine Coolent temp isn't parked at the 3 oclock position all the time. For the most part, it hangs out 2 lines just below the 3 oclock position. First noticed 2 weeks ago.

3. Boost no longer feels like the ARD tune, it feels stock. First happened a week ago. I stepped on the gas a few times, and the boost finally came back. Now, I cannot get it to hold boost beyond what feels like stock, maybe below that. Turbo is still spinning, I can hear the 'woosh' when I let off the gas.

4. Codes pulled: P0455 (normal), P0442, P0108, P0171.

5. Corrective action done: I cleaned the MAF and Idle Control Valve and cleared the codes. We will see how that works tomorrow.

Anyone have any ideas or tips on getting this under control?

 

Based on the temp gauge I'd first suspect the engine coolant temp sensor. You can measure its resistance/voltage to test or just guess and drop in a new one if its old. It could also be a vacuum leak. Start by inspecting all obvious hoses - but you may also have a leak going to the evap system so if nothing is obvious you may want to try a test (see RSPI's DIY vid on Youtube for doing a home made smoker). Was the intake oily when you cleaned the ICV and MAF? If so you may want to check for a clogged PCV (ie pull the dip stick when running to see if any smoke comes out and do a rubber glove test on the oil filler cap). After those tests I'd check out the fuel pressure.