need advice on upgrade

Here's the deal. My truck has about 310k on it now and it's starting to feel a little lazier than it's newer days. I tow a skid steer loader pretty much on a daily basis and I need a little more power. I've been going out of town quite a bit lately and the hills are killing me. It wouldn't be so bad, but the truck is always shifting into the next gear as i'm going up the hill. I can't afford a new truck at the moment, and I really don't want to look for a new engine or tranny yet.

I was thinking about getting a mild chip, because I heard that they modify the shift points and give a bit more power. The truck still starts easy and doesn't smoke or anything so I'm assuming it has some more life in it. If the chip helps me out then I would definately do a downpipe and intake soon after. If it doesn't do anything then I'd be reluctant to do anymore upgrades.

I would like to get the chip asap. Wildman and Dp both look tied up at the moment, should I wait for one of them or look at something else? Also what are some recommendations for someone in my position?
What kind of tests can I do to see if pissing in the wind?