1990 Ford F-150 high idle and ruff running

I am a single female not knowing much about vehicles! And not much money for repairs. But I own a 1990 F150 4x4 that the idle just races most of the time. I can go up the road at about 25 mile an hour and not touch the gas. Not easy to stop on icy roads. And then there are times when the idle is normal and the engine just does not want to idle, it sounds like sucking on straw and wants to quit. When I step on the gas it coughs and then goes or stalls. I have ask friends and they are baffled. Please what can I try myself, before spending alot of money. Thank you so much for your time.