Reps. John T. Doolittle and Richard W. Pombo joined forces with former House Majority Leader Tom DeLay of Texas to oppose an investigation by federal banking regulators into the affairs of Houston millionaire Charles Hurwitz, documents recently obtained by The Times show. The Federal Deposit Insurance Corp. was seeking $300 million from Hurwitz for his role in the collapse of a Texas savings and loan that cost taxpayers $1.6 billion. The investigation was ultimately dropped