Rough idleing after pressure wash engine and fuel injector clean

Hi,
I'm assuming you added fuel injector cleaner to your fuel tank rather than using a direct pressure cleaner through your fuel injectors.
When a solvent/cleaner product is added to your fuel tank, carbonaceous deposits (basically the dirt and gunk accumulated over years) are flushed through the fuel system. This can cause major problems if the contaminants manage to enter your fuel pump and make their way past the seals. This can and has damaged good fuel pumps. Downstream of the pump is the fuel filter - once deposits reach the fuel filter, they may block it and reduce fuel flow. The next major problem areas are the injectors themselves (rather sensitive to dirty fuel) and the engine.
Fuel injector cleaner is not a product I would recommend using. Many major car manufacturer's have recently issued memos to repairers blacklisting the use of cleaner products due to the downstream damage that may potentially be caused by them.
You should replace your fuel filter once you've finished using the tank of injector cleaner. This is most likely the problem (and could have probably used a replacement anyway). I hope this solves your problem. Otherwise you should check your fuel line pressure to ensure the pump is supplying what is required. Failing this, your injectors are probably the next most likely culprit. By this stage, things are starting to get expensive so lets hope the problem is just a blocked filter!
On a related side note; pressure cleaning an engine can sometimes cause water and soap to push down beside the spark plugs in a spark ignition engine. Sometimes this will cause the engine to run a little rough until the heat of combustion burns the contaminants away.
Hope this helps, Sherwin