4.0 swap issues

[ObscureAuto]

Hey all, I'm really stuck. I put a 1994 explorer motor in my bronco 2 and when it works it works great! When it gets warmed up however it starts to misfire REALLY bad to the point where it's undrivable. What's weird is it misses for about 20-30 seconds then it'll clear up, all power is suddenly back and runs smooth for a bit then it repeats the cycle.

I have replaced MAF, coil pack, plugs, wires, ensured all the injectors are good (I never want to take that I take off again...) and a whole heap of other parts. Only cel I have is for EGR. Blocking off EGR on the intake didn't help or hurt. I'm sure there is a lot of other things I've replaced but that's all I can think of for now.

Only thing really that I haven't touched is the fuel pump/pumps (can't remember if this had dual pumps or not).

Any help would be much appreciated because I miss driving this truck dearly..

 

[franklin2]

What happens when you drive it with the O2 sensors unplugged?

 

[gaz]

@ObscureAuto
The 1994 Explorer 4.0l has a single fuel pump, location, the fuel sender unit mounted inside the of fuel tank.

 

[bobbywalter]

evap and vac issues when egr cycling likely. can you get a 94 non egr pcm? cant remember if they were straight across in 94