Please help me I have a 2005 Ford Explorer 4.0 V6 that idles up and down

[Phillystpete]

I purchased this truck off my boss the 250,000 MI all highway it ran fine one day there was a little Miss change the spark plugs and the wires. Then it was showing misfire cylinder 3 running rich replace the injector didn't help so I replaced all the injectors still didn't help still idles up and down wants to stall when it's at a stop or in Park. when you're driving it it seems to run just fine and when it's not you just turn on the AC and under load it seems to run okay.
Okay here goes I've replaced all injectors and gaskets there is definitely not a vacuum leak I've replace the EGR the temperature control sensor the fuel rail sensor all for O2 sensors I had a mechanic drill the holes in the catalytic converters he said they were black but they were still okay.
it seems to keep getting worse and worse with every part I put on it.
I put an after-market EGR valve on there that I bought off of eBay the only thing I could think is it might be that four wheeler fuel pump cause this problem I've spent every penny I have trying to resolve this I've had three professional mechanic look at it and the friend of mine everyone says the same thing we keep throwing Parts at it amount of money to throw any more I'm disabled and a senior citizen can somebody please advise me what to do next thank you

 

[Mbrooks420]

What do you mean 4 wheeler fuel pump?
Check engine light? Have you replaced the intake gaskets?

 

[Phillystpete]

What do you mean 4 wheeler fuel pump?
Check engine light? Have you replaced the intake gaskets?

What do you mean 4 wheeler fuel pump?
Check engine light? Have you replaced the intake gaskets?

 

[Phillystpete]

What do you mean 4 wheeler fuel pump?
Check engine light? Have you replaced the intake gaskets?

 

[Phillystpete]

It should have said fuel filter not 4 wheeler.
Previous owner set check engine light had been on for years only now it flashes unless speed is increased like over 30 miles an hour or when the AC is on.
And yes I change the gaskets

 

[Mbrooks420]

If the check engine is blinking you are misfiring. Are you sure your plug wires are correct? They don’t line up on the coils like you’d expect them to.

What’s the fuel pressure?

 

[Phillystpete]

At one point the coach said misfire cylinder 3 I replaced the fuel injector I had put in and also that plug wire when you start the engine up it has a slight shake them Works itself out it.
One mechanic told me he check the fuel pressure when I change the plugs and wires I didn't change the coil pack but like I mentioned the check engine light doesn't always Flash when it does I accelerate and it stops and it only flashes now and then