85 Buick Century Bucks Under Load

I have an 85 Buick Century 150,000mi 2.5L TBI with an acceleration problem. Under low to modetare loads it bucks. Even with TCC unpluged. Plugs, wires, cap were replaced. Problem started soon after having ignition module replaced. While power braking and looking at the fuel injector you can see the fuel momentarily stop spraying when it bucks. Where does injector get its reference from? Could it be the ignition module, MAF sensor, does it have one and if so where is it located? Thank you for and advice.