Loss in top end / speed acceleration

I recently changed diff gear ratio from 5.40 to 4.11 (due to to reduction in tire size). The end performance resulted in top end speed reducing to 85mph @ 3500rpm in 5th gear. Will not accelerate past this due to the engine cut out. I do know that the computer needs to be re calibrated, and I am looking to find a good programmer in order to do this. Any recommendations you can give me would be appreciated. Thanks.

- Tony Graybill