Sounds like they replace the EGR sensor, by what you are describing. So I would hazzard that you have a2.0L motor in your car (so you have either a LX or a ES Protege)
The EGR valve is very comon on the protege's. Causes to the car to run rough, stall, hard start, shake, hard hard brake pedal. These sorts of things
There are however two other problems that are starting to show themselves o nthe protege's as they get older. Now by problems I don't mean 'oh my god this car is crap!".I mean things that happen to all cars with age.
The two other common rough running problems are:
1. Leaking Intake gaskets (around 2.0-3.0 hrs to fix)
2. There have been cases of ignition coil failures (your car has two). IF THIS is not attended to quickly a misfire could damage the front catalitic convertor. Coils are around the $50-100 mark plus.5 hours labor. CATS are worth big $$$$ so get it checked out
OH! Almost forgot. Some shops were still selling the original EGR valves even though Mazda came up with a revised part ## a few years ago. SO there is an outsiode chance that the EGR failed again.
Hope this helps
Cosmo. Mazda TEch
Tuesday, March 13th, 2007 AT 2:17 PM