Should have installed trans go shift kit while the trans pan was off.
Is the cooler plugged into the factory trans cooler lines? If so, those fail at the crimps going from metal to rubber.
How long ago was snout coupler changed? Was new fluid used? If not, change it, $10-20 for fluid from the dealer. Also inspect for seepage from around the snout/rotor pack area, some do not use the correct sealant there.
Replace all vacuum lines.
Change LIM gaskets with Felpro MS98014T and swap out the coolant elbows while you're in there, GM Elbows or Dorman aluminum ones with GM O rings.
Unless the vehicle has metal LIM gaskets already. Easiest way to check is to look at the side of the gasket at the front or rear of the engine, if black, its plastic and needs changing ASAP, if silver, its fine. It seems coolant elbows can almost always be an area of concern. Aluminum elbows with GM O rings might be the best short term solution. Long term concern is aluminum oxide build up.
Flush the cooling system well. My current coolant suggestion is Zerex G-05. Can be had at napa for a reasonable price. From what I have gathered, one of the best coolants available.
You can't check boost without some tool that will scan live parameters. 5-7 PSI WOT is considered normal. If less, question vac leaks or failing BBV actuator.
