Iowa’s Attorney General says his department’s investigation of last summer’s gasoline price spikes found some companies held onto supplies to try to make the spikes last longer. Attorneys General from Iowa and other states helped conduct last year’s F-T-C investigation of gasoline price hikes. Attorney General Tom Miller says while it is legal for companies to keep their gas off the market even when supplies are low, it’s a troubling development for consumers. Miller isn’t calling for a law that would ban the practice, but he says government officials should carefully monitor the actions of gasoline suppliers. Miller’s own wallet took a big hit last summer when gas prices rose. Miller drives a gas-guzzling S-U-V, and admits — with a laugh — that it’s inconsistent with his views about energy conservation.