Why is my truck misfiring?

I have a 2001 ford ranger 3.0 v6 with 100k miles on it. It's been misfiring but mainly in the low end of my tachometer. It was annoying and hard to accelerate without getting the car to shake. I changed the coil pack and all spark plugs. It seemed to work normal for about half a week then started acting up again. Now I'm contemplating on changing the spark plug wires also. Can bad wires cause misfires? I always thought they just effected gas mileage. Also if I replace them should I get OE or OEM wires or is it something simple enough it would matter what brand?

Absolutely bad wires can cause misfires. OEM is best, but premium quality name brands also work. Just avoid the economy versions. Read this post on misfires

http://ricksfreeautorepairadvice.com/fix-misfire-problems/

Bad wires cause misfire, usually under a load, OE wires are OK.

Yea, just start changing parts, you'll eventually get it fixed…

Proper diagnosis is always the best way to solve any problem. To do that, you need specialty equipment, especially with cars. If you don't have any of that, you can use a few regular tools to try to help you. Check maximum coil outputs through to each plug end by inserting a screwdriver or something similar into each plug wire, one at a time. Hold it about a half and inch from a ground and start motor. Spark should be strong, consistent, and blue. If it isn't, the wire or cap is open or corroded. Replacement is always the best way to go. Look or listen for vacuum leaks from hoses or gaskets. Fuel filter clogging is also a normal problem.