Pinging and lose of power when pulling up hill

Hello, "pinging" is a sign of spark knock which is often something that occurs with pre-detonation of ignition from timing issues -- or fuel / air / spark ratio issues. Also, there was no carbureted engines in 1990 Ford's - so are you sure this is a 1990 model? Engine performance diagnostic testing is required regardless. Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops