When the car is at idle it will miss and then the idle will start to wander, sometimes almost to the point of stalling. I am trying to help a friend out and normally don't mess with mazda's or 4 cylinder cars. Why would it be missing?

The engine threw a code a few weeks ago and it said "massive egr vacume leak" i tried finding a leak in the egr system, but i couldn't find one. The plugs and wires have been replaced.

 

What year 626 and what was the code #? Do not remember ever seeing a massive EGR leak code.

 

it is an 03 and no i do not remember the code number offhand

 

Maybe the EGR valve is sticking open a little. Is this a US car? Last year of 626 was in 2002 in the US. How many miles are on the odometer?

 

It is a US car, it probably is a 2002. It has 60k ish miles.

 

Several things you might give a look to that have run across in the past. Vacuum diaphram for fuel pressure regualtor ruptured that draws fuel directly in to the intake thru the vacuum supply hose. Hose connects to manifold at the #3 intake runner so #3 plug will be all black and fuel fouled. Intake manifold gasket blown out, usually at the bottom, outer corner of the #1 or #4 runner. Mass air flow sensor contaminated. When running rough, disconnect the sensor and see if condition improves considerably.