just bought a 17' skeeter w/ 87 evinrude 110hp vro. sat for 3-5 yrs. always has hard start cold but ran great 1st 3 outings. filled tank w/gas on lake ran great wot appx 15mins then lost power can go 6mph max(2000 rpm max) , any more throttle stalls, soft bulb, i replaced old (probably original) fuel line, no change, cleaned & gapped plugs, no change. sometimes alarm will sound short beeps, tonight while alarm sounding got some speed, alarm beeps were faster when engine faster, then stalled and alarm constant til turned off key. also there is a small knob under key - what is it? any help greatly appreciated.