If the fuel distributor is changed, I'd recommend changing the injectors and plugs at the same time.
I would have the entire fuel-system checked starting with the fuel lines and pumps/relay. Then have a look at the idle control valve. If you suspect its the OVP, have an alternative OVP plugged in and observe the engine behaviour before paying for it.
126 tailed by a 203, 129 leading the pack.