Ford Repair: rough idle, fuel delivery system, 1995 ford windstar

Question
Hello I've been working on my 1995 Ford Windstar for a few weeks now. Since then I've replaced the gas filter, air filter ,oil/filter, icv ,plugs and wires,and both cats.Whats it is duing rough idle,spits and sputters no pickup,when you floor it,it bogs down especially when on high way won't go into overdrive or passing it bogs no power.Now it pings like marbles. I don't know if its because of the crappy gas where using is the high grade. Also changed trans oil/filter.  Thank you  I'm a fellow Mechanic.  Just very confused.


Answer
First I would like to apologize for not getting back to you sooner. I had some families issues that required attention and was away from my computer for a few days. I believe your problem is in the fuel delivery system. My first thought was that you have a clogged injector. After further though, I want you to do this, run a fuel pressure test on the van. If your a mechanic, then you will no to run the gauge at all rpm's. Let me know what you find out. One other thing, make sure that the firing order is correct to the coil pack, just out of curiosity. I look forward to hearing back from you, and again, sorry for the wait.