Here's the problem. When I punch on the gas from idle or below around 2800rpm the car hesitates and backfires. If I take off slowly it runs fine. It idles normal and it drives normal once it's going. I've changed plugs, wires and fuel filter. No leaks are coming from the valve cover because I changed that not too long ago also. I also put some fuel injector cleaner in Saturday and that didn't help. I've asked people and I've heard everything from timing, bad/clogged fuel injector, bad ignition coil, to a vacuum leak. If anyone can point me in the right direction I would really appreciate it.