If your car has drivability problems (stalling, bad mileage, roughness, etc.), a diagnosis is ALWAYS in order.
Did you know that today's cars can have as many as 3 computers each controlling separate systems? If it's not already obvious, this is NOT a job for discount tire and brake shops! Specialized equipment and training is required, and you would be wise to seek out a shop with ASE Master Technicians!
Remember to check back tomorrow for another helpful tip!