Need recommendation for a code scanner

[4x4hunter]

2004 Kodiak 4500 crew cab hauler body. We transport yachts and powerboats.

This unit has been towed 4 times in 500 miles. Engine RPMs drop to 2200 and won't pull.

5 dealerships, along with GM tech. support, can't figure it out. Of course, they can't make it display the same problem when they have their diagnostic equipment hooked up. They've made an unnecessary turbo. change and two fuel filter changes.

Can anyone recommend a decent aftermarket code scanner that we can keep hooked up until it goes into "limp mode" again? Then we can give GM the numbers. Scanner has to display the numbers, not your hinky "count the flashing light" type.

Thanks.

[dmaxalliTech]

GM has a flight data recorder type device that stays plugged in and mounts in a cup holder, when your problem occurs, you hit the button and then they can download that info into a computer and review it.

[More Power]

The current crop of tuners/programmers all have the capability to read/reset trouble codes. This one feature alone could be worth the price of admission.

A Duramax 6600/Allison powered C4500 attended this year's Pull-Off (http://www.thedieselpage.com/features/pulloff04.htm). The owner had installed a 40 hp tune during the event using a Predator programmer. Worked well.

MP