Premium Fuel?

so i topped my tank off with premium fuel from Shell... u know the V-Power. well today when i was driving i stopped at a local pub came back to my car 25 minutes later and the engine wont turn over. last night and through this morning the engine was idiling rough, and had a much more aggressive tone to it. even though it did sound better i knew something was wrong. any way i am assuming that it's either a clogged fuel filter, or a clogged fuel pump. more likely the fuel pump. the car is a 1988 Cutlass Cierra 3.8L, its only got 69,9xx miles on it. my question is, is the fuel pump in tank or out of tank, and if it is out of tank is it reachable by just merely going under the car. i know that if u tap it sometimes the pump will break free. i am getting it towed tuesday, today is sunday, but i would like to cancel that if i can drive it up to my mechanic. your responses are much appreciated.

The fuel pump is in the tank. You have to remove the tank to get ti it.
Try changine the filter first. and see if its any better. It should be underneath the car just in front of the tank.
The fill - up is likely unrelated to this failure, but its posilbe there was a lot of water or dirt in the gas.

Any one have any experience with ever - ware 3 step fuel system cleaner? My local firestone has suggested.