2000 Buick with loads of problems.

My 2000 Buick Lesabre Custom has the starting problem everyone else seems to have. I have to floor it to get it to start. I will look at the idle air control later but I have other things wrong with it.

When it start it, I feel a hugh vibrations from the engine. When I put it into drive, it is still there till i get to about 30 MPH then the vibration stops. However I feel like I lost power cause I can't go over 75 MPH. At a traffic light, I have to floor the brake to get the car to stop. Even if I let go of the brake, the car wants to go as if it is getting gas.

What can I do to help my car. Is there more information you guys need?

Thanks

It would help if you could have it scanned & report the DTC's so we know where to start. If you don't have a scanner, take it to any national parts store, they will do it free of charge. Any coolant loss lately?

Okay it has been a month and I got time to do the reading.

P0304 - Cylinder #4 Misfire

Did the following.

Replace all the spark plug cables and spark plugs.
Delete reading and still there.
Reran the OBD2 reading, still came up P0304.
Replaced the the ignition coil for the #4.
Delete reading and still there.
Reran the OBD2 reading, still came up P0304.

I have no idea where to go next.

Unplug all the elec connections at the coil packs there may be a bad connection.