Engine choking and stalling after hard acceleration

[NeoSHNIK]

Hey guys, I really need some advice, because my little Z is very sick...

Story:
My car has 55000 miles, mostly stock, except for K&N air drop-in filters and FI exhaust.

1. In January I had two cold starts (long story, but I had no choice...) and I got a Service Engine Soon Light because of that. The codes said - "5th cylinder misfire, 2x Cold Start".
In response I cleaned and recharged my K&N filters (thought it might cause misfire), and reset the battery to get rid of the SES.

2. Car drove fine for 2 months. Then last Friday after a fast turn and acceleration the engine was choking on something. I had pedal to the floor, but the car was going slow and jerking a bit. Engine stalled as I was rolling down a highway... I restarted the engine and it seemed fine after that.

3. Yesterday I got a SES as soon as I started the car, and it read - 0300 - Random Misfires. After some serious forum reading, I decided to clean the MAF sensors and reset the battery. 50 miles later, the SES hasn't came back.

4. I was expecting HP and MPG gain after cleaning the MAF sensors, but instead both were worse. Car seemed slow and MPG was crappy. At one redlight I floored it and after about 65 mph engine started choking, I lost all power and engine stalled. I restarted the car, and it was still doing that even at low rpm. Ended up restarting the engine 2-3 times and finally pulling over. No smoke, engine bay seemed normal. When I looked at the air filters - one of them was dripping with that red K&N oil. The air filter bay had a small pool of oil. So I waited, let the oil drip out. Then I was able to get home and clean the filter from all the excess oil.

Questions:
Do you think the problems my car is having is because of the excess oil in the K&N air filters?

What do I do now? Now that I don't have excess oil, I plan to clean MAF sensors again. But then what? Anything else I should do?

Thanks a lot!!