My 89 Honda's idle will not go down after starting, I have checked the throttle cable and tried to lower the idle, but it still goes to 1500-2000 rpms in N or P and I have to shut it off in D4 with lights or the ac on to prevent the engine from shutting off hard at high rpm's. I'm taking it to the mechanic next week and am just wondering what to expect.

Is it a vacuum leak? there are many hoses and does this model have an idle sensor that might have gone out?...

It is Carbuerated, but only has 94k on it and has been well maintained.

Thank You for any advice

 

you mentioned it is carbureted,so dont hold this information to me, because i dont know what is different on a carbureted engine.
but supposing i was diagnosing any other car,this sounds like an adjustment is needed between the iacv(idle air control valve) and the tps(throttle position sensor)

 

Don't know anything about carb 3g's, sorry but try following the diagnostic step in this service manual.