Starts and idles great, but if I try to go above 3000 rpm a steady alarm goes off and the motor starts shuddering. I've changed plugs, hoses, filters, thermostat, thermosensor, oil pressure sensor and fuel supply float. All of the above were suggested by various technitions. I'm now being told that it could be the Thottle position sensor (TPS) or an airflow sensor. Has anybody had a similar problem?