2001 Ford Mustang Cutting Out

Did you check for applicable trouble codes? A cylinder miss-fire should set a code? Around here, some of the national brand auto stores will check codes for free. To check codes, yourself, at the least, you need an obd2 code reader. With a cylinder code, you can check fuel--spark--compression on that cylinder.

Check proper fuel pressure. I saw what you replaced, but, how long since over-all tune-up?

I am not sure because i just bought it from someone and they have let it sit for 2 years. He told me that all it needed was a temperature sensor and I replaced the ECT and the sensor on the back of the head. I live too far away from the parts store and do not own a code reader. Also the water is very brown and rusty so i know i need to do a flush.

I'd give it a tune-up. Go from there. It's going be hard for me to track it down, unless you can do some diagnostics? I can't see much from here.