Here's my problem:

(rough idling) While idling, engine will heel over every so often.
(decreased MPG) Have noticed a significant decrease in MPG in the past few weeks. I thought it was due to ethonal being added to the gas, but after further investivation no one adds ethonal here in Southern Louisiana.

Oil, oil filter and sir filter were changed 3,500 miles ago.
Check air filter, looks clean.
Have not checked fuel filter, I don't think that's the issue with 28,000 miles on the vehicle (It's not like I'm adding farm diesel to my car.)

I'm afraid to take it to the shop because there are no dependable automachanics here. Every wants $.

I think it might be the spark plugs. What do you think? If advice on which spark plugs to choose?

'05 roadster