Yaleaagor

I recently bought a 1984 mustang SVO. The man said it didnt run. It cranks and cranks until we spray starting fluid and then it'll fire up right away. Somebody said it could be a bad fuel filter or a faulty fuel pump. I was wondering if I could get a few suggestions on what it may be?
Also, when you step on the gas the engine doesn't roar louder like how it does in most cars. It's extremely difficult to keep it idling while on gear. However, it idles alright when out of gear.