I am currently trying to get a handle on the oil consumpation of my 04 TJ with a 4.0. A Borla header, high perfomance cat, and cat back system where all installed in Oct. I hadn't driven much since I was running a company truck, but now it's back to daily driver duty and I have noticed a lot of oil usage. I had a few senors on the intake throw codes (TPS,IAC) and had severe carbon build on on them. I have cleaned them up, cleaned the CCV lines and hoses to the intake, replaced the elbows. It seems to be pulling oil into the intake throw the elbows in the vavle cover. I have tried putting filters into the elbows to catch the oil but allow the pressure to out. That seemed to slow it down but then it started pushing oil out of the oil pump drive/camshaft position sensor. Has anyone else had trouble like this? Could switching form a full sythentic to a blend help?