Gilder completed three rounds at 14-under 199, one better than second-round leader Mark Brooks at Glen Oaks Country Club in West Des Moines, Iowa.
Brooks essentially cost himself his first Champions Tour victory after bogeying the final two holes, carding a round of 3-under 68 and ending at 13-under 200.
Rod Spittle and Mike Goodes both shot 6-under 65s to claim a share of third place one shot further back at minus-12.
Mark Calcavecchia took fifth after managing a 2-under 69.
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