Mitsubishi Repair: Low Idle Problem with 01 Galant, crankcase pressure, pvc valve

Question
I have a 01 galant which ran perfectly a few weeks ago. I had just bought it and saw that the spark plugs could need replaced. I went down a bought some platinum spark plugs and a new PVC valve. The new spark plugs were exactly the same as the old ones. The car now has a problem with low idle. If a start the car in park it will idle fine, but if I drop it into drive, while depressing the brake it sometimes drops from about 3/4 of 1000x to 1/2 of 1000x. A few times it has stalled, but it just idles rough until a give it some gas.  It also seems to happen more often if I accelerate quickly and stop hard. Any info would be greatly appreciated. Thanks

Answer
Morgan,
I have had a similar problem when I had replaced a PCV valve.  I had bought one from the local auto parts store, and after I installed it, my idle was very bad.  After stepping on the gas a few times, it was fine.  It turned out the PCV valve was stuck and did not regulate the crankcase pressure like it should have.  

If you still have your old PCV valve, try reinstalling it and see if your idle returns to normal.  Also check to be sure the little hose that goes from your PCV valve to your intake manifold is secure with no leaks.  If you find your new PCV valve is the problem, return it and go out an get a new PCV valve from the dealership.  The ones they sell at the dealership are usually about the same price as an aftermarket one, and are better quality.  
Good luck!