Ford: 95 mustang gt (shakes hard), mass air flow sensor, mass air flow

Question
I have a 95 mustang gt. About a month ago I noticed it was shakeing a little bit.This only happend when I started the car.Some times it starts fine with no problems runs great,and then other times I start it and it shakes like crazy and runs like crap!So what i did was change the spark plugs and got some new msd wires, cap and rotor, and a new msd coil.The car seemed to run better for a minute.The car still shake. I have checked the spark from the cap, the wires, and the plugs.I dont have a problem there.Well the car shakes so hard that my mufflers cracked on both sides, and my coil bracket broke last week I had to remove my tail pipes because they were dragging.The car is pretty much stock exept for bbk shortys mass air flow sensor cold air intake. It also has a new alternator, battery,and pos neg battery cables.Like I said one minute it runs great the next minute it shakes.Any ideas on what I can check to fix this problem?Please help. Thanks

Answer
ok the first thing to ck would be take a look at the harmonic balance  make sure it is not coming apart and look close to see if the rubber is coming out.do you have a ck eng light and if so what are the codes ? if not ck fuel psi and you should have 32 to 34 psi at idle and 42 to 46 when you unplug the vacumm.let me know .