Hi, Ive been using this forum for advise and troubleshooting for 6 mnths now so I thought I may aswell join the revolution.
Ive got two main issues that are bugging the hell out of me... 1st is as above the car starts up cold and sounds fairly sweet. I usually leave it idling for 3-4 minutes before setting off on cold mornings. Drives fairly sweet until engine reaches temp and then gets a bit sluggish, acceleration isnt as responsive. I'm wondering if its an O2 sensor issue as I believe they dont really kick in until the engines warm but im no expert and Ive heard there are four o2 sensors? My money is on the one near the exhaust manifold but I'm wondering if anyone else is/has experienced this and could let me know if i'm completely barking up the wrong tree. Any advise greatley appreciated?

2nd problem is a slight murmour when idling. The needle doesnt move but there's a slight skip beat cracking off ICV? Plugs?