Sputtering on acceleration

My van has been in the shop three times and they still have been unable to find the problem. After making sure the fuel pump was good, cleaning the fuel injectors, and running through the computer, now they tell me the only thing left to do is rebuild the engine. Here is the problem. When the van is in idle or reverse it starts puttering really bad. It had never stalled but it feels like it is going to. Sometimes I can feel it while driviing, also. Any help would be greatly appreciated

No, the engine light has never been on. Can a do-it-yourselfer change the idle control valve or should I leave this up to the professionals. Thanks for such a prompt response

One more quick question. Will the engine light be on if it is the valve, or not all the time. Also, does one have to remove the throttle body or can yoiu replace the IAC in place. Once again thanks

Thank you, you have been such a help. So basically all I need to do is remove the air resonator assembly and the throttle body will be there. Then I would unplug the IAC connector and then unbolt the IAC Valve. Then just replace it with a new one and hope that is the problem. Does that sound right or am I missing something.

If you don't mind, how is the IAC attached. To the throttle plate?

Thanks, you have been a great help. I am going to order the part an attempt to do this. Any last words of encoragement? I would leave you feedback but I do not have enough points.

I just ordered the part and will be here tommorow. I will let you know if that was the problem. Thanks again.

I just changed the IAC valve and thought it was better. However, when I turned on the air conditioner the the hammering or puttering is really bad. So now that we ruled the IAC out do you have any other ideas? Could this problem all be tied into the air conditoner. I checked the refrigerant pressure and it is fine. I also used throttle body cleaner and cleaned out the throttle body which did not help.