The average price for regular gasoline at U.S. filling stations increased 3.74 cents over the past two weeks and may have peaked, according to Trilby Lundberg, the president of Lundberg Survey Inc. The price jump to $3.9671 a gallon covers the period ended April 6 and is based on the Camarillo, California-based company’s survey of about 2,500 stations. “Price hikes at the pump have been losing steam for weeks,’’ Lundberg said today in a telephone interview. “Crude oil prices have slipped and if they don’t rebound in the very near future, gasoline prices will peak very soon, if they haven’t already.’’ The highest price in the lower 48 U.S. states among the cities surveyed was in Chicago, where the average was $4.45 a gallon, Lundberg said. The lowest price was in Tulsa, Oklahoma, where customers paid an average of $3.66.