Timing belt is being changed this week, just bought it Saturday. Needs a lot of tune up work. Plugs, cap and rotor, timing belt, and a carb rebuild kit.
I wasn't sure if they were intended to run on premium or not, or if the archaic ECU (if any) detected such changes in octane. It's a combination of factors it seems contributing to the poor drivability, I just don't know if this is one of them.
Fuel for the confusion:
http://www.automobilemag.com/green/r...rid_sedan.html
Notes the HF uses premium. I do not have the car with me ATM to check the owner manual either.