I have a 1990 ford ranger... What I wrong with it?

What is your question?

My truck is loud and it shakes. We replaced the air filter, fuel filter, plugs and wires. I added seafoam to the gas tank and nothing is helping. I have to keep my foot on the gas at all times or it dies. It doesn't go over 15 mph 95% of the time. What else could be wrong with it?

How long has your 1990 Ford Ranger had this problem?

About a month or 2