windstar missfiring on 1st and 3rd cylinders

I have a 2000 ford windstar 3.8L. It is missing at idle and accel. I took it to my shop and he has replace all the plugs, wires, coil pack and three injectors with no change. What else can be causing the miss. There are no code that he can see. Please help me with this my wife is about to kill me if she does not get her van back soon!!!!!!!!!!!!!

how many miles on the engine...

73,000 miles

check the intake gaskets these are bad about leaking also have your mechanic load the engine until it begins to miss then unplug the egr valve, if the miss goes away then the egr passages will need to be cleaned

also decarbon the engine..could help

Of course you can also disconnect the vacuum control to your EGR valve yourself and drive the vehicle to see if the problem clears up.