Engine misfiring Please help

I dont post on here much i usually just read through other peoples problems.
I am having a misfire issue that comes and goes. It idles fine but when I drive it, it starts cutting out. If I'm at a steady speed it don't really do it but the more gas I give it the worse it gets.

I got good compression and im getting fire to the plugs. Sometimes when i go to WOT it will run like a bat out of hell and then the next time i punch it it wont. Im thinking about changing the distributor with another one i got laying around to see if that will help.
It also seems like the more timing i give it the better it runs so i was thinkin it might not be advancing the timing like it is supposed to.

well any way my car has a
306
roush 200 heads
E303 cam
24 lbs. injector
C&l maf
Typhoon intake with throttle body
replaced plugs wires and coil in mine
Any advice would be Greatly appreciated also thanks.

Thanks
Colby

Sorry i forgot to mention i did check the codes the only one i got was
Insufficient EGR flow so i cleaned the egr valve and i havent checked them agian since i done that.

It seems to be worse when its cold but it is still there when its warm. It is the most noticeable at cruise speeds above 2500 rpms it clears itself up.

Now i adjusted the timing to where it seems to run better but is a little jerky taking off. My timing is also way over whats it is supposed to be. I had it set at 16 with spout out now it is over 20 i just adjusted it to where it sounded the best. That makes me a little nervous.

I have been thinking with the setup i have would a good tune help or a decent MAF and a tune help my issue?