How to diagnose and fix poor acceleration in an Audi 80?

I've noticed that my Audi 80 is experiencing poor acceleration, especially when starting from a stop or trying to overtake. I've checked the spark plugs and air filter, but they seem to be in good condition. What could be causing this issue and how can I fix it?

First, check the fuel filter and fuel pump to ensure they are not clogged or malfunctioning. This could be causing a lack of fuel flow, resulting in poor acceleration.

It's also important to check the ignition system, including the ignition coils, distributor cap, and rotor. If these are worn or faulty, it can lead to weak spark and poor acceleration.