BATON ROUGE (AP) — Booming oil prices that have come to Louisiana’s rescue when other income sources have dropped recently may not be enough to fill in revenue gaps next year. Corporate taxes and personal income taxes have fallen, and the state sales tax remains flat, leaving Louisiana’s revenue buoyed mainly by oil and gas prices that continued to rise. But with a downturn in the economy and oil prices falling below their previous highs, economists said the 2009-10 fiscal year could be a challenging year for Louisiana’s finances.