also i would check the firing order because cylinders number 5 and 7 are too easy to mix-up. on another note, one cylinder may not be firing. to check it: with the engine running remove the wire from the spark plug and slowly take the wire away from the plug. you should hear it ignite and as you take the wire away the engine will sligthly slow down, if everything is fine with that cylinder. if the engine doesnt slow down, there is something wrong with that cylinder. put the wire back on the plug and repeat for all cylinders. there are special pliers to do this so you dont get shocked from the ignition.