My 1989 Toyota Tercel hatchback 5 speed starts fine, then after a few minutes it starts to idle really high, I'd tell you the RPMs but it does not have the meter (good call Toyota) It drives just fine except at stops where the engine starts going nuts and would most likely overheat if l sit in too much traffic.

l know it can be a million things wrong but does anyone have a suggestions as to what it most likely is? Also any fixes l can try before bringing it in? And about how much will it cost?

Take a look under the hood for a lose vacuum hose around the intake manifold (under the air cleaner). You might see if the throttle is getting stuck just a little open & if it is replace it or put on a little stronger spring. With the car off, have somebody pump the gas petal a couple times to find the end of the cable, l am not sure if an 89 has a carburetor or fuel injection but the cable will go to either one & u will see where u can rev it up from under the hood & just open it a little & let go letting it snap back to the closed position & let off lightly to see if it is sticking. See if u can just ''stomp'' (open/close real fast) the gas peddle when it does it while ur driving to see if it stops & if it does fix the spring.