I recently bought a 1992 with 106K miles. I've replaced all the fluids, filters, and plugs(purchased plugs from dealer). Car runs great when cold. Once it warms up it appears to lose power; the transmission doesn't shift properly. On a few occasions it has stalled when accelerating from a stop. The car idles fine, smooth acceleration but feels bogged down after it warms up. I've replaced the fuel filter and catalytic converter. Any suggestions what else may be the problem. Could it be a fuel pump? HELP