jf951

had the headgasket replaced ran terrible sounded like the straight six in a jeep, then replaced the O2 sensor (the coolant after a blown HG can damage 02 sensor so i'm told), ran great responsive quiet and powerful for a couple days but now runs really lifeless again 2nd,3rd,4th terrible performance. motor is just noise and buzzing with no go...are these still symptoms of running rich? what else should i look at? idles at 850rpm and smooth but alot of noise btwn 2300 and 2900rpm.
89 s
MAF
MBC
testpipe
k27/8
thanks