Missing under acceleration, comes and goes

[onesmartidiot]

I have a 4.0 OHV 1999 explorer, I just did a tune up about 4 months ago new plugs and HALF of the new wires (couldnt get the driver side wires through the intake) Runs fantastic and gets about 22mpg now.

Basically, sometimes I can start it up and it will let me take right off. Others it will idle perfectly until I take off, then it misses for a couple seconds, even If i try to floor it rpms will not go above 4k. I push the clutch and let it idle (perfectly) and about 5 seconds later its good to go, perfect as ever.

CEL is on, however its usually just because I have a leak in my filler neck for the gast tank. I am going to advance today to have them read it to double check, but I didnt know if anyone around here has had this issue and advice on something I may be overlooking.

-Blain

 

[onesmartidiot]

Did a laundry list of repairs in 2014, issue was stuck somewhere between leaking intake, cam sensor, and weak fuel pump.

The motor still drops power in the 3500 rpm mark which is no big deal, most of my juice is from idle to 3000. Next fix is a 5.0 swap.

 

[koda2000]

In my experience, missing under load is always ignition related. I'd change the other 3 spark plug wires, check for cracked plug insulators and corroded coil pack. If you can't route the plug wires the right way, run them any safe way you can.