It sounds to me like the shop might be trying to rip you off. Your MAF should have lasted longer than that and that's too much $ for a new one. Before taking the shop's word for it that the MAF is shot, I'd look at the MAF myself and if everything's intact, I'd clean it. All you need to do is spray the wire element with a spray cleaner that does not leave a residue on the wire (or you can use an eye dropper to drop drops of rubbing alcohol on the wire) and then let the wire air dry. Do NOT touch the wire with anything like a Q-tip or rag to clean it. If you still have an engine problem, I'd have another shop check it out to make sure its caused by the MAF. If you have to buy a MAF, shop around at parts stores and junk yards for the cheapest unit. Its very easy to clean or replace yourself, or have a mechanical-minded buddy help you. Don't shell out $425 for a new MAF just because one shop says yours is shot and that's the parts and labor cost for a new one.
Bright Red 2003 Edge Plus, 3.0 liter, reg. cab, 4WD, manual trans., 4.10 rear end.
Mods: Speedliner spray-on bed liner. Air box mod. K&N drop in air filter. Gibson Sweptside single pipe catback system. James Duff traction bars (above the springs type). Delta Industries black polyethelene truck box (mounted on the driver's side of the pickup box between wheel well and cab). Hidden Hitch receiver hitch. Side window visors. Door pockets.