I got this 08 LGT 122k miles, with cross-threaded spark plug threads (previous owner was trying to fix a misfire), I retapped the threads & put in a Helicoil. Also just did a timing belt job on it while putting the head back on. I got it running again and on the first start up, this thing runs like dog sh*t. The only codes it's showing is for the front o2 sensor.
It ran pretty rough before I fixed the spark plug and had misfire codes for all 4 cylinders, and when I took the timing cover off it looked like the tensioner plunger failed and may have cause the engine to jump time (timing marks were off about a tooth).
There's also a massive exhaust leak coming from around/under the turbo area that I haven't been able to fully track down.
Could this thing have a bad PCM and what's the best way to determine that? Or what would be the ideal tests to run and things to check first? All the plugs and coils LOOKED new. And could the exhaust leak make it run so rough? Any input is appreciated