88 2.9l popping and missing under a load going up step grades

[88 XLT Ranger]

Need help on this strange issue

I got an 88 Ranger 2.9l it runs fine until going up step highway grades. It starts loosing power than I hear a popping nose and missing feeling. I pull over shut it off let it site a while start it up its fine. Other times after going up the steep grade and than levels out for 3 miles on the highway as I go down the off ramp stop than go it does it again pooping missing. I was thinking fuel filter? hell I don't have a clue. Any help is very much appreciated

 

[RonD]

Yes, change fuel filter, first.

Driving uphill at speed is the highest demand for fuel, so either fuel pump is weak or fuel filter is limiting flow, fuel filter is $10.

And it doesn't do it at highway speeds, so not spark related, high RPM

If you can rent or get a fuel pressure gauge you should see 30-40psi engine idling.
Then raise RPM to about 2,000 and hold it there, pressure should go down a bit then hold steady, not continue to drop.
Then shut engine off, pressure should drop but hold steady above 20psi........for a few months, but for testing 10 minutes is fine

Also check throttle cable, it may be stretched and you can't get full throttle(WOT) anymore.
Push gas pedal to the floor, put something heavy on it or use a stick against the seat.
Then see if you can open the throttle more at the engine end of the cable.
If so you need to do the "throttle cable mod", google it.
Very easy to do.

At WOT(wide open throttle) the computer ignores O2 sensors and runs engine Rich for max power, your problem reads like mix is getting lean.
Computer reads throttle position with the TPS, it expects a voltage from TPS above 4.5volts before it enters WOT and runs engine richer.
So if throttle cable isn't opening throttle plate all the way anymore then no WOT

 

[88 XLT Ranger]

Yes, change fuel filter, first.

Driving uphill at speed is the highest demand for fuel, so either fuel pump is weak or fuel filter is limiting flow, fuel filter is $10.

And it doesn't do it at highway speeds, so not spark related, high RPM

If you can rent or get a fuel pressure gauge you should see 30-40psi engine idling.
Then raise RPM to about 2,000 and hold it there, pressure should go down a bit then hold steady, not continue to drop.
Then shut engine off, pressure should drop but hold steady above 20psi........for a few months, but for testing 10 minutes is fine

Also check throttle cable, it may be stretched and you can't get full throttle(WOT) anymore.
Push gas pedal to the floor, put something heavy on it or use a stick against the seat.
Then see if you can open the throttle more at the engine end of the cable.
If so you need to do the "throttle cable mod", google it.
Very easy to do.

At WOT(wide open throttle) the computer ignores O2 sensors and runs engine Rich for max power, your problem reads like mix is getting lean.
Computer reads throttle position with the TPS, it expects a voltage from TPS above 4.5volts before it enters WOT and runs engine richer.
So if throttle cable isn't opening throttle plate all the way anymore then no WOT

Thank you Ron

I will run down to Napa get a fuel filter if not that will try your other options. Thanks for the help its so much appreciated