To run at 3k RPM with the throttle closed it's getting air from somewhere - you need air for the engine to run at that RPM so it's getting it somewhere. If the throttle is closed you have a leak. And that means unmetered air which means it's going to be running lean and that will drive up the temp and run the fuel trims positive if it's even attempting closed loop operation.
Fix the vacuum leak first.
Or swap in an EJ22 and get more power without the messy unreliable turbo EA garbage.
Or.... yeah..... burn it and get a V8. Although I would sell it to some other sucker and forgo the weenie roast.
GD