I have a 97 Chevy Monte Carlo, 98000 miles, 3.1 Liter. While you are driving at speeds from 45-70mph if you begin to lightly accelerate it will hesitate/stutter. If you accelerate agressively, no hesitation. If you touch the brakes to disengage to torque converter, it stops. When its on a computer, at rest, you get random misfires on all cylinders and while driving you will get random missfires. Parts that were replaced: plugs, wires, coil packs, ignition module. The Mapp sensor was cleaned and checked. The O2 sensors were also checked. Other than the torque converter what else could the problem be? Thanks in advance for the help.

clean your EGR valve and check your catalytic convertor this will cause hesitation and randomn misfiring if clogged exspecaily at high and slow speeds, to much back pressure on motor