Maybe somebody can help me with a problem that my 94 LT1 Z28 decided to have...

After I got back from I parked my car on the street cause I was going somewhere else later on....

Well I jump in my car and started her up and it had this weird vibration that rattled my interior while the engine was running, I go to turn on the heat and everything in my car is vibrating worse and the it sounded like it was going to quit.....
The exhaust sound changed from sound like a stock V8 to a cammed V8, so I turned the heat off but I still got a vibration like the first time... The idle hovers at 500- 650rpms but mainly at 500 in gear and park, I know its supposed to be around 700 or so, so I gradualy reved the rpms up and the vibrations was still there

Well I put my car into gear and the vibration has gotten worse and then turned on the heat and everything was rattling more worse than before...

So I listened to my exhaust and it sounded like I was running on 7 cylinders but when I drove it I still had the power of all 8 cylinders and no vibrations.... There are no vaccum leaks what so ever....What gives???

I have come down with some thoughts in what might be wrong...
1. Ignition Coil
2. Ignition Module
3. Plug wires
4. Opti
5. o2 Sensors

Can anybody help me???

Thanks