My Topaz with 88,000 miles on it is beginning to fail me. When I start it up, the engine races up to 2000rpms immediately and after about 5 minutes or so it idles down. If I drive off before it idles down then using the accelerator makes it go slower. Anyhoooo, now it overheats and sprays the winshield with antifreeze (on the inside). Does this mean I have a BAD THERMOSTAT or does it just mean it is time to put the Topaz out to pasture?