Ok driving myself insane trying to figure out what is wrong with my car. Have a 90' RS 305 that has a "shake" when idiling at a stop and seems to not be taking off well from a stop. When I gas it from a stop it seems like revs up fine but transmission maybe won't keep up with it idk if I am explaining it right. I've changed almost all electrical tune up stuff inc. plugs, distrub cap and rotor, wires. They seem to help for a day only then the problem came back. Thought maybe something with the fuel pump at first but the problem goes away after I get to about 30 mph. I don't have a problem driving at high speeds or uphill. Anyone have any ideas on what it could be? Also checked for vacuum leaks found a small one fixed it but nothing

 

You said when you changed the plugs it helped but it comes back sounds like your losing and cylinder. When you pulled the plugs did you have any fouled or really black heavy carbon on any of the plugs. A quick troubleshooting pull one plug wire off at the distributor at a time and see if the engine rpm does not change if it does not change than the cylinder is not firing. Pull that spark plug and look at it if it looks ok then do a compression test you have to have aleast 90 psi but it should be around 150. Do compression test on all the cylinders there should not be more than 30 psi difference between all the cylinders. Could be carbon build on the vavle seats causing a loss on compression

 

Thank you there was only one plug that was dark I can't remember which one it was but will try the distributor wire trick and then check compression. It's so annoying now all of a sudden my infl rest light stays on...

 

Check the code. Take a jumper wire or paperclip cross the A and B terminals and the check engine light will start flashing its like Morse code it will start one flash then 2 flashes three times then if there a code if will do the same thing and then it will go back to code 12. Then look upthe code hope this helps

 

Disassemble your injectors and soak em in lacquer thinner for about 3 - 4 hours; put em back together with NEW O-rings.

The air bag light is a separate problem, don't let it tempt you to stray from the path of fixing the other problem.