1993 BMW 525i Still having power issues when I step on the

I just got back from the mechanic and spent $200 on a fuel system cleansing and replacement of spark plugs. Drove away, and nothing has changed. When I press on the gas, I get close to zero power. When I let off it and flutter the gas pedal, I get a little bit more power. I thought the problem would stop once I got the fuel injectors cleaned, but there is no change. However, the mechanic said I need a new FAN CLUTCH. My question is, could a new fan clutch fix this problem, or does it seem unrelated? With the exception of a new left sway bar needed, the mechanic says everything looks good. He did say I should get a new serpentine belt. Could that be causeing the problem. Thanks so much for taking the time to read this!