"As designed" meaning that time, wear and neglect has left most all these cars slower than they should be and they are no longer running right. Getting everything working correctly first is exactly what you should do before you ever consider changing things from stock.

Adjusting the ALDA is just a bandaid to cover up other problems that need to be fixed. If everything is working properly then adjusting the ADLA should only increase black smoke out the tailpipe. If you adjust it and there is a major gain in acceleration then your engine/injection pump has a big problem.