Concerning the scan tool:
I bought an ALDL cable/data logger from Moates that I used for a while and it was great. Moates doesn't sell them anymore, but it seems like BoostedNW has stepped in to sell a direct replacement. You'll need a laptop and winALDL or TunerRT (I honestly thought WinALDL was easier to set up and more than adequate for just verifying sensors, although neither are difficult to use)
Having said all of that, if you ever think you might want to alter the tune on this truck I would read up about Flash EBL II as a complete replacement for the stock ECM and not even bother shelling out the cash for a dedicated scan tool or an ALDL cable (as long as you have a laptop)
Not saying that you NEED to spend money on either of these things to make your truck run, but being able to interface with the computer that's controlling your engine will help you rule a lot of stuff out quickly.
Also, does it surge at idle when it warms up or is it just when you hit the gas/are at cruising speed?