ok i have a 1986 Mazda RX7 with a StreetPort Rotary Engine, but every time I start my car i have to hold down the gas pedal and then when it starts it shakes the whole car. Does anyone have any ideas why i have to hold down the gas pedal and why my car shakes so much?

 

I'm not 100% sure on this, but I believe in the s5's if you hold the gas pedal down all the way with the car off, it cuts your fuel off. This could mean that your car has a problem with flooding, and merely requires the fuel to be switched off for the first second or two to get the engine turning over.

 

still with out holding down the gas pedal the car turns over but there is no catch so i have to hold down the gas pedal a little

 

Try this:before you Start it up "completely",Roll the engine over like usual.for about ONE second,then Pull a spark Plug..Check it to see if it is Wet with Fuel
It sounds like the car is Flooding,and if so,you'll need to get the injectors cleaned.