1989 Ford Thunderbird a tune up gone wrong

It depends what is disconnected. Somewhere in the fresh air tube is the mass air flow sensor. Chrysler is the only manufacturer that has been able to make an engine run right without using that sensor. For everyone else, all the air going into the engine must go through that sensor. It measures the weight of the air and uses that to calculate fuel metering. When any air sneaks into the engine that doesn't go through it, there will be no fuel to go with it either. That includes vacuum leaks and any leaks in the fresh air tube.