I don't really know what kind of car do you have so I will just put it in genaral. I would check the distributor and the "ignition control modual".Sometime cleaning the air intake might help too ( just get the carburetor cleanner and spay it in while starting it..just to help it open and close better).
It is likely that you have a bad ground in the system... check all the ground wires
Check your fuel filter. When was the last time you also checked your air filter.
There are so many options as to where you can get your air filter in your vehicle checked. You can go to any automotive repair store and they will be able to check it for you. You can also go to a car dealership and they can check it for you.
Assuming you have checked the bulbs, check the brake light switch.
Check the ignition module & pickup. You may find the problem there.
Check fuses and relays
check the thermostatic switch(turns on and off fan) check engine temp sensor ect.
check out the starter......
I have a 2003 Highlander. Whenever I get the oil changed, the check engine light comes on within a couple of days. I finally figured out that there is a hose under the air filter case that gets disconnected when the filter is checked. Just reattach the hose and the light will reset after a few restarts of the engine.
check fuses and relays and flasher and go from there
Check for a broken motor mount. Also make sure you are using the correct filter and have not changed brands.Check for a broken motor mount. Also make sure you are using the correct filter and have not changed brands.