1999 Other Jeep Models Cause of P020 misfire codes

Our '99 Grand Cherokee LTD with the 4.7 L V-8 has had an issue with only occasional eratic idle, and a fuel cleansing from the local Jeep dealer helped alot for awhile. While towing an enclosed trailer long distance, the check engine light appeared and stayed on for the next week. The speedometer seems to have occasional rapid fluctuations of approximately 2-4 mph. The Jeep also has the tach 'bouncing' while traveling at a constant speed down the road. It acts almost as if the lock-up torque converter is unlocking and then relocking repeatedly. While the diagnostic computer was attached to the vehicle it detected the misfire codes P0201 and multiiple other cylinders are involved. Also cylinder #1 was only firing maybe one out of every 6-8 cycles. The local independent shop that read the codes mentioned that the only other vehicle they have seem with this same problem of misfires was a Durango with the same 4.7 L and it needed an entirely new ECM to solve the problem. They are not sure that ours will need the same. With the expense of a new ECM, we are hoping to get a more specific answer. Do you have any ideas or information?