Where should I start or what should I do??

Can you pull the transmission and flywheel, install a new clutch and re-install the trans? Do you have tools and a transmission jack?

Are u being a smart ass or really trying to help? Homestly do it sound like I need to replace the clutch?

That is the straight truth.

Is it a pull clutch ( cable operated ) or hydraulic ??? If it's a pull clutch it could be just a stretched cable

Or you might have to replace the clutch . The parts needed would be , Pilot bearing , clutch disc , pressure plate , throw-out bearing , and slave cylinder if it's a hydraulic clutch

Sure sounds like it needs a clutch, but the problem could be the throwout bearing. The drive shaft, transmission cross member, transmission and possibly part of the exhaust needs to be removed to access the clutch. The clutch assy. is then removed and the flywheel should be removed for surfacing. Then the flywheel reinstalled and the new clutch components (disk, pressure plate, pilot bearing and trow out bearing) need to be installed. This would not be a good diy job for an inexperienced person. Flywheel bolts should be replaced and torqued with a torque wrench. How many miles are on this Mustang?

check the clutch pedal linkage first, if its hydraulic master or slave cylinder is bad