Regular fuel wouldn't make a difference like that. Here's what you do.

New fuel filter
New spark plugs
A reputable fuel system cleaner (Lucas, Redline, etc.)


When this is complete, pull the ground strap off the negative battery terminal. Go inside. Make sandwich. Eat sandwich. Come back out, reconnect negative, start car. Drive car. Smile.


If this doesn't work then you have some serious problems and we'll go from there if it's still bad. If this doesn't fix it and it's from a dealer I would start bitching because it's going to get extremely expensive to diagnose and fix.