1991 Mazda 323 Hatch 1.6 stalls only in Drive
 

Hey everyone, I am new to Mazda's and need some insight. My sisters Mazda idles fine in park, neutral, and reverse but as soon as it is put in drive, second, or first gear, the car stalls immediately. The only noticeable problem it has is a really bad valve cover gasket leak. Oil is all over the place and on the spark plugs. We cleaned the spark plugs and checked hoses for cracks and leaks assuming it might be an air or vacuum issue but same problem occurred after adding some clamps, etc although it did start and idle stronger. It has oil and transmission fluid in it. Inspected the throttle body and Air Mass Meter and it all looked clean. I have gotten several different opinions such as the torque converter or fuel filter. Need this fixed by tonight if possible so any pertinent information would help. The car will drive if I give it gas in neutral and then shift in drive but it has really bad loss of power and if dropped in idle it dies. Thanks.

Just a quick update. Got the car here to my place a few minutes ago. It sat in drive just fine and idled. Cut the car off and tried it again and it stayed idling. When I first got to the car and tried starting it, it died every time in drive. So possibly its safe to say the issue refrains once the engine has heated up and at operating temperature? Thanks again everyone.

Ok everyone, final update. I think we have narrowed it down to an exhaust issue. As I was bringing the car here I heard some poppy exhaust sounds kind of like a tuners exhaust would sound possibly. Could this be the catalytic converter? Thanks.

You have a misfire for whatever reason that allows unburned fuel into the exhaust and there it ignites.