I agree with [MENTION=94]Stingin' Away[/MENTION] here assuming it's not a high pressure fuel pump issue. In the manual, it is recommended that you use only "top tier" fuels in the car (because of the additives in their fuel -- see toptiergas.com for a list) and also they recommend using an additive like Chevron Techron which contains a very strong solvent (a polyetheramine) that dissolves carbon deposits every 6,000 miles at oil change intervals.