why am i seeing at idle a large variance in A/F in CL? my NB gauge shows burried lean and then swings to just short of rich. my WB shows 15.5 down to high 13's. this is idle. at CL "cruise" i see about 15.0/1 and to about 14.0/1. should i not be seeing around a swing of 14.5 to 14.9/1 ? also after prolonged idle i am seeing it go (goofy?) occasionally in WB from a very lean to very rich like 12.9 to 16/1 again CL at 200 F. then my CE comes on and i get lean code. now in all fairness i also have been getting ECU and prom codes when engine at prolonged idle. this may be prom or ECU related but NEVER happens when on xway at cruise speeds or when vehicle moving in city trafficeven after a long period of use. i thought was snap on ZIF but removed that and still occurs. fact of only idle rules out ECU/prom failure does it not? i am thinking of running OL to see how my WB A/F looks. weather here stable now so wont see large temp swings AM to PM.