RX8Club.com - guys I need help...

I've been trying to figure this out for months now. It started right after I installed my midpipe, but I'm thinking it's not the prob although I'm not crossing it out as a reason yet. I've got studdering problems under hard exceleration around 6g all the way to red line but mostly in the upper range at about 8. 3rd gear was the worst but now it's doing it in other gears too. My gas mileage is super shitty now too. I for the life of me can't figure it out. I've tried everything from cleaning the MAF...changing the airfilter...new mounts...."which Mazda told me to do"...F-ing idiots. Um...I've reset the ECU a couple of times. When I cleaned the MAF I found oil in my intake which means it was overfilled. I cleaned that all up...including the intake tube which had bits of oil sitting in it too for god knows how long. After doing all that I took it out and it ran great for about a day. Now it's back to the same shit only worse and the only thing I can think of now is one of three things: A...fuel pump going out. I've searched and found they can go out at around 60g and my car is at 57g. B.....the midpipe although I don't understand how that can be. And C....the oil that got spit back up into the intake is causing more trouble than I'm aware of. ANYBODY...please help me out here.... My car is a 04 57g on it...coils replaced last august and spark plugs replaced a few months ago. I do have a cel, but its for the midpipe...which sometimes turns off and I don't understand that either, but whatever. Anyway...anything at all would be helpful