Anyone know how much a fix for this would be?
Car was driving good for about a week and all of a sudden on my way home it started shaking upon acceleration and the engine light came on and started flashing.The car would also shake when stopped. It would start shaking at like 40 mph and then be good but start once again at 60 and then be good. But if i hit the gas pedal really really really slow and accelerate it would be all good.. Anyone know what it could be?

 

First and cheapest step is to swap the coil on that cylinder with another one, clear the codes, and see if the misfire follows the coil. It's easy to do. If you don't have a coil puller tool, just make a loop of a beefy enough zip tie and wiggle it out with that.

If the misfire moves with the coil, replace that coil (replace all of them if they haven't been done in a while--they're not expensive). If that fails, pull the #3 spark plug and inspect it. You can replace it (or all plugs) and see if that fixes it. If it's any deeper than that, I usually take it somewhere.