I just answered a post about this and I don't mean to be redundant but maybe I can bring out some of the better minds here. I have noticed over the last few years all my cars seem to take longer to crank when cold and seem to idle a little rougher when in open loop. Here in Bucks County we get the oxygenated fuel in winter as well as a different blend than areas of PA without the emission requirements. My 91 Z-34 Lumina had an especially odd problem of stalling at low speed and long cranking time. After pulling the TSB's I found one describing the problem. GM says "the lower volatility/increased driveability index of newer fuels" can cause this. In the 91 I changed to a GM updated PROM and it made a big difference. If I drive to Lehigh County to see my daughter at school and gas up there I see as much as 2 MPG improvement in the 89 IROC. In Calif Suzuki had a problem with the Hyabusa sport bike dying after 100 or less miles out of the showroom. Thier engineers found that the particulate size of the fuel additives were plugging up the fuel filters. At my friends shop we got into this and he also said he is seeing a lot of vehicles coming in with plugged filters also. I am wondering if this is shades of things to come. Years ago the 89 fired before the crank made a complete revolution. Now it takes more time on a cold start. Anybody out there have some comments?