engine misfires then ok
 

2000 grand marquis, 152,000 miles. Whats happening is sort of weird that ive never exerienced this before but whats happening is the car will run fine and then all of a sudden out of the blue it will just misfire and litterally "chug" almost like driving a car with a blown head gasket and blowing black smoke.

But this is the part that confuses me, when it does this i turn the car off and start it right back up and its fine again. It will run great for a while and then all of a sudden this happens and its getting more and more frequent to the point of about every 10 minutes, but everytime if i turn the car off and start it right back up it goes back to normal.

Seeing how something is being reset when i restart it it leads me to believe that its some sort of sensor or some monitoring device on the engine, but i have no clue what to look at.

What i have done is changed all the plugs, and all 4 o2 sensors and recently just changed the intake manifold (was cracked).

Thanks