Idles up and down after warm, but goes away in reverse and drive. 1993 honda accord

I`ve replaced both idle air and the fast idle thermo-valve twice and still have same problem I`ve replaced both idle air and the fast idle thermo-valve twice and still have same problem

replace the idle air control valve and check ur coolant bypass hoses for blockage(corrosion) replace as nedded and refill coolant to proper level...also bleed the system of air....it can be other things but this is most common solution........ replace the idle air control valve and check ur coolant bypass hoses for blockage(corrosion) replace as nedded and refill coolant to proper level...also bleed the system of air....it can be other things but this is most common solution........