Land Rover Repair: 1999 land rover disco II (iacv), mass air sensor, air flow meter

Question
I recently replaced the O2 sensors on my 1999 land rover disco II, after doing so it started running sluggish. I cleaned the (IACV) and the mass air sensor. I’m 90% sure it is the Idle Air Control valve. Just don’t want to spend $300.00 if there is another option; like a cleaning product.  I took the (IACV) off and tried cleaning it. Then it seized up and would not open or close.  Finally I got it to open and close and the truck ran better. Now its started again and I think the valve is not opening and closing properly.  Any info will be helpful at this point.

Answer
I have never had to change an IACV on a Discovery II.  It is not unheard of, but it is a rare thing.  Failure of this part, however, would not cause it to run sluggish. It would only affect the idle.  From your description, I would say it is more likely to be an air flow meter.  You could also check the fuel pressure.  The first place to start, however, would be to check to see whch, if any, fault codes are stored.