dod Problem after DOD delete

[Burban2007]

I recently did a dod delete on my 2007 suburban. 6.0 200,000 miles. I thought the problem was the afm lifters being that there was a tick at highway speeds. I only had a tick at highway speeds. If I drove on the street I would never get the noise. As soon as I held a steady speed on the highway I would get what sounds like a lifter tick. The dod delete work was done by a Preformance shop. I do not think that dod was the problem. If I hold the throttle steady at 2000rpm while in park I can get the tick to come on. After I let the engine idle about 2-3 minutes the tick goes away. As soon as I hold the rpms back up it will come back and repeat the process. No loss of power while this is happening and no other sounds. Oil pressure is about 10-15 at idle and close to 40 while on highway. I would greatly appreciate any help.