thanks for the replies. Had some oil drained to proper level, but symptoms still there. It really had nothing to do with the oil, I suppose. Instead I checked the sparkplugs and found 1 bad. Had all 4 replaced na also the wires, then I cleaned the distributor cap and the contact points in the MAF sensor. Idle seems to be more stable plus nawala rin yung pagbaba ng rpm pag nag-oon ang aux fan. So far so good. Hope it stays this way