Difficulties with hitting step temperatures and stuck sparge. Been there, done that, made a mess, didn't get the beer I wanted. So, I made some changes.
First, I added a fine-mesh bag to my mash/lauter tun (it's made of "voile", a fine polyester cloth used by BIAB brewers). The bag gives a greatly increased area for the wort to filter through. The bag sits on a bazooka filter and several pieces of copper tubing to ensure there's plenty of space between the bottom of the bag and the bottom of the MLT for the wort to drain into. No stuck sparges/mashes since. Hose down the bag after use and re-use indefinitely.
Second, I set up a HERMS system using my pump to circulate the wort through a 25-foot copper coil immersed in my electric brew kettle - I gave up on gas-fired mashing. (The heating element is rated at 5,500 W at 240 Volts. Ohm's Law showed that it would give about 1,200 W at 120 V - please correct me if I've done something stupid with Ohm's Law. Operating the element at 120 V means I can use a Johnson temperature controller to control the temperature of my brew kettle. The sensor goes inside a copper tube immersed in the water bath/brew kettle and the element plugs into the temperature controller. The wort coming out of the heat exchanger is exactly the temperature of the water bath. Controlling the temperature of the water in the brew kettle lets me hit my steps very accurately. I plug the element into a 240 V outlet when I want to raise the temperature of the water quickly, then switch to 120 V to let the temperature controller fine tune and maintain the temperature. Don't try building one of these if you don't have a good understanding of home wiring and electricity! If you're familiar with electrical wiring check http://theelectricbrewery.com/ for detailed information.)
HERMS eliminates the problem of getting your mash heated evenly, denaturing some of the enzymes, and potentially scorching. If you don't want to switch from gas to electricity you could probably still hit your steps better with a heat exchanger coil in a gas-fired water bath, you'd just have to pay more attention than I care to devote. If you have an immersion chiller, it will work as your heat exchanger. If you don't have one you can buy 60 feet of 3/8 inch for $110 at Lowes web site; I think they have it in shorter lengths in the store.
Hope this helps.
Dan