I have a 2003 pontiac vibe and I keep having the same problem with it. Has a rough idle and when I put my foot on the gas a chirping sound comes from the back and the engine light starts flashing. Originally changed out the coils and plugs. This fixed the problem for about 3 months, everything was perfect but now I'm having the same problem about once every 6 weeks. Each time it has been a different coil that has gone bad. With the warranty they keep replacing them and my car runs great until another 6 weeks passes. Engine light just came back on and once again its the same thing. What would keep causing this?

SOURCE: 1999 pontiac grand prix . will not run

If wiggling the wires cured the code, then one of the wires is broken inside the insulation. Pull on each wire one at a time. look for the colored insulation to stretch, this will be the broken wire. For the other car that wont rev up, this is a common when the catalytic concverter is plugged up. This will also cause MAF codes, and in turn, TRAC OFF light.
See http://www.greatautohelp.com

SOURCE: 96 firebird is having problems,

Have you ran a diagnotic check to see what codes are coming up?
Throwing parts at the problem will get expensive. It will also ruin other parts (Like your catalytic converter), when your engine is misfiring and not running properly. Your vehicle is an OBDII system, fix the problems in the order they appear (then clear, run and recheck)...meaning, one problem can cause another and so on. Fixing one problem may correct the other ones too.
You may get lucky with the shotgun approach, but usually not.
Run a diagnostic test, at least you'll know where to start looking for the problem.

SOURCE: Reoccuring Dead Spark Plug Coil on 2003 vibe

Check you spark plug and engine ground. if one of those is causing too much resistance then it can overload the coil.

I saw that one, on one of my cars and it was the spark plug that was loose but the car was not missing fire, it was just having too much resistance and overloading the coil.

SOURCE: Car coded yesterday p0303 noe check engine light flashing

The only thing left is the injector or a vacuum leak on the manifold gasket sucking air in and causing a lean condition. Thats is its the only common issue providing you dont have a head gasket issue leaking coolant on that cylinder and the compression and valves are not leaking. The old spark plug should show a coolant issue if present. The white part will be shiney if you have a coolant loss. If the coolant is looking real dark you should have the cooling system checked for gas being pushed into the cooling system on compression stroke thru the head gasket.

SOURCE: 2005 Pontiac Sunfire. No start condition this

Timing is off, did you replace the wires as well? Check the timing?