My 1987 Volvo 740 GLE wagon automatic Gasoline is idling at 1500 rpm. The engine starts at 800 rpm but it will reach 1500 rpm right away and it won't kick down. I don't think there is air leak but I might be wrong. Anyone have any helpful ideas what is causing the high idle? Thanks in advance

It's possible that the computer is responding to an improper sender like either the Coolant Temp Sensor (CTS) or the Idle Air Valve (IAV) isn't moving like it should. Both will need proper hands-on diag to verify if they are the culprit.