Diesel Bombers - Are my injectors going bad?

I recently bought a 2005 3500 4x4 with the 5.9l. it gets great milage and doesn't have any probles starting up. 4x4 works great, it has 143,000mi on it and just had a new transmission put in it less than 1000mi ago along with new tires. The guy had sold it for his son who left for vet school and said his son did all of the maintenance on time and becuase it was so clean and everyrthing including all of the fluids checked out that I could see, I bought it for 16k and thought i got a good deal on it.

I noticed a few days after buying it that if i rev the rpms up, it will temporarily hang, followed by staggering back to its idling rpm range. I have never owned a diesel before and i wasn't sure if this was a unique quality to expect out of a diesel.

I took it to Truck Stop Performance in San Antonio, and they told me that because it hangs like it does, i am gonna need new injectors. the previous owner had given me a quadzilla stealth tuner that he said his son had used for better fuel economy. It wasn't modified in any other way, other than a K&N and so i didn't have any particualr reason to think he was using it for pulls or goofing off. The mechanic said that they can be particularly hard on the high pressure common rail and that it likely damaged the injectors and i need to get them along with an airdog.

It runs fin never stalls, no smoke, no hard starts, but i fear that i might have bought a truck with an expensive problem. should I take it to a dealer? is there any specific diagnostics to check out if it's just one particular injector? please give me peace of mind.