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98 explorer starts, runs rough then dies.

98exsport

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Feb 16, 2017
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Vehicle Year
1998
Make / Model
Ford
Transmission
Automatic
Hi all, I have a 98 sport with the 4.0 SOHC. 3 years ago I bought it in hopes of fixing it and using it for summer weekends in the mountains. The truck ran then but had a misfire in cylinder 6. I traced it back to a stuck intake valve and a thrown cam follower. Long story short I removed the engine and prepped it for a top end rebuild (truck has beautiful compression and less than 100k).

It sat torn down and covered for 2.5 years until I finally was able to undertake the project. I ordered rebuild heads, a new timing set, and a head gasket\seal and gasket set (With new oil pump and water pump).
I cleaned it and put everything back together (using the OTC cam tool) put the engine back in the explorer and tried to start it. First time i tried the fuel pump was shot, no sound at all. I replaced the fuel pump and primed the system (I could hear the pump again and checked at the rail schrader valve for fuel). cranked it and it would fire and rev to about 2k and search for a few seconds then stall. I tried to give it gas a few times while cranking and got it to rev to 2-3k with alot of pedal feathering...very hard go all it wanted to do was stall. After about the third time cranking and giving it gas I managed to get it to stay running but at 1-1.5k rpm. If I tried to give it fuel it would start to stall but if I touched nothing it would run fairly well for five mins then stagger and die. Temp was good, fuel rails and injectors aren't leaking, its a brand new battery, its new fuel (drained the tank and purged the lines before storing it),they're brand new plugs and wires and I spent over eight hours triple checking for vacuum leaks. I changed out the injectors with clean units I had, removed the upper intake and replaced the rubber gaskets a second time, I swapped an IAC and TPS from my brothers 98 (That runs) and no luck. I'm at a loss here. Any thoughts?
 
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RangerFabWorks

The O.G blackwidow67
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Lexington, North Carolina
Vehicle Year
1990
Make / Model
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Engine Size
302
Transmission
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Sounds like the lower intake has a leak. Or the mass airflow is bad. What happens if you unplug the maf?
 

98exsport

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Joined
Feb 16, 2017
Messages
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0
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Vehicle Year
1998
Make / Model
Ford
Transmission
Automatic
There is no change when the MAF is unplugged and I replaced the intake gaskets a second time yesterday just to be sure. Its absolutely perplexing
 

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