Hi guys
I have owned my impreza sti since december last year without performance issues. A couple of weeks ago the eml came on for front o2 sensor. After checking and clearing the code I now have jerking and hesitation around 10psi and a large loss of power but then goes to 20psi but feels shakey and still low power. Both sensors were changed and still the same but no eml. Spark plugs were inspected and show alot of white on the tips, they are only 3k miles old. Compression shows 135 on all 4 cylinders. I found a hole in the turbo inlet hose which I changed for a mishimoto silicone hose. Still having same issues along with overheating after a long run. Head gasket test was done and did not change colour. Vaccuum is stable at just over 20inHg. It has a decat exhaust, and valve delete and should be hittin around 350bhp. Please can someone help with this we are running out of ideas and I have searched everything!