Lets talk clutches and flywheels, cause i need help!!

[v8vinny]

alright here is the scoop:
2003 mach 1 32v 4.6. alright i'm having a problem with my clutch slipping. i bought the car off a customer of mine. i did all the upgrades and service on it too. I buy the car with 42000 on it cltuch is fine. Got stuck in traffic on a big hill on highway the other day, and pedal got stiff due to stop go stop go, and i couldnt pull over cuz i was already pushed to the shoulder. Now the clutch holds normally, but if i mash on the gas w/traction off out of the whole i get a wierd studder that feels like cltuch slipage. I'm currently diagnosing the car, but im so busy with other work i cant get it in the bay, so its sitting and i just take it out on the weekends. Now i was searching for new clutches and flywheels. My main concern is will a LIGHTWEIGHT FLYWHEEL throw off the balance of the motor, has anyone used one yet on this motor?? also what type of clutch i've used SPEC before and i like the stage 2+ anyone have a say on that. Or let me ask your opinion on the best flywheel/cltuch package, or just stick with my flywheel have it resurface and get a new clutch, Thanks guys.