PCM swap engine stalling

I swapped a 2003 PCM into a 2002 Monte Carlo same engine and transmission. 3.4 liter and 4T65E. The trans is from a 2004 car. Apparently the pressure manifold switch was changed in 2003 and I was having problems with the car shifting with the 2002 PCM. It shifts fine with the 2003 PCM but when I give it a lot of throttle off idle it will drop about 200 RPM and stall. The car runs great with the original PCM but it will not shift out of 2nd gear. I had the original 2002 PCM reflashed with the 2003 trans data and but it did not work. Hoping to get some advice on getting the engine to run better with the 2003 PCM. The tuner said the engine data was virtually identical between the 2 PCMs.

Are the 2003 and 2002 PCM's the same P/N?

Yes they are the same service number. I meant to mention that in the original post thanks for the reminder.