"Occasionally" when I stop and go in reverse truck starts chugging, i.e. sounds like it's missing, running really rough. If I put it in neutral and rev up it will usually go away. Vacuum leak? Injectors? Roughly 76,000 miles.

 

At 76k, I think I'd change the spark plugs - and the fuel filter if it hasn't been done in the last 30k.

 

Okay, thanks GLC, yesterday the check engine icon lit up, how can I check codes? 06 lariat w/ message center.

 

most local auto parts stores will check the codes for free.
You have a misfire. The code will tell you which cylinder. At that point, you need to determine if it is a plug, cop or injector. 76k miles, it's hard to guess. Plugs are the cheapest so start there.

 

Post the exact numeric codes, not the verbal interpretation.

 

Po345 Cam position sensor, sensor A, Bank 2

 

I know exactly what you are talking about. Mine did the same too. I'd like to say that I am certain your problem is cam phasers which isn't exactly good news but I replaced mine and it fixed the problem for a while but returned after about 6 months.