Stalling issues during hard acceleration (1 Viewer)

[n54zach]

My '98 has been having stalling issues for the past year or so that began to occur rarely and has recently gotten worse. It will drive and shift fine but whenever I attempt to accelerate hard (foot to the floor) it stalls out, and the second I let off the gas it returns to normal. I have also had some rough starts recently as well. There are no check engine lights, and does not appear to correlate with engine or outside temperature. I also have some odd smells after longer trips, not sure if related or not.

So far I have: replaced air filter, load tested alternator, cleaned MAF and throttle body, replaced fuel pump and filter, and ran injector cleaner with a full tank of 93. None of these have had an effect so I am beginning to believe this is an electrical or transmission issue. I've heard about the early 100s having EFI fuse issues, so I checked the fuse and connectors in the block and everything looked fine to me. I am planning on doing a trans fluid flush as I'm sure the fluid is nasty and old this week.

Anyway, I'm pretty stumped at this point and not sure what to do next. Would like to avoid throwing more parts and money at a problem that I keep misdiagnosing so curious if anyone has any insight on where I should go from here. Thanks

 

[Eighteen11R]

Assuming the '98 has an internal fuel pump? Did you replace the fuel strainer when you did the pump? Could be you have some debris inside the tank near the fuel pick up?

 

[n54zach]

Assuming the '98 has an internal fuel pump? Did you replace the fuel strainer when you did the pump? Could be you have some debris inside the tank near the fuel pick up?

Yep replaced the strainer. When I replaced the filter some nasty stuff came out, looked like dirt but suppose it could be rust? The truck has rust but not bad enough to where I'm concerned about the tank but I suppose it could be possible. Or it could be from 200k of crappy gas from rural gas stations. Anyway I read on another thread that the injectors on the 4.7 will always function regardless of how dirty the gas is so I feel like fuel isn't the issue

 

[Eighteen11R]

Only presents under heavy throttle suggests fuel starvation in my experience. I had the same problem with my low mileage 1st Gen Bronco. Debris in the tank, over time and due to more aggressive/off-road undulations loosened alien creatures from the bottom of her fuel bag and slowly, over time, developed starvation under heavy suck/hard acceleration resulting in my 5.0 H/O FE to begin coughing/wheezing... As you've advised, taking your foot off the long skinny pedal and she ran fine around town...

With everything you've already done, the time and miles on your rig, you may need to drop the tank and purge the that lurk in her fuel bag.

 

[n54zach]

Only presents under heavy throttle suggests fuel starvation in my experience. I had the same problem with my low mileage 1st Gen Bronco. Debris in the tank, over time and due to more aggressive/off-road undulations loosened alien creatures from the bottom of her fuel bag and slowly, over time, developed starvation under heavy suck/hard acceleration resulting in my 5.0 H/O FE to begin coughing/wheezing... As you've advised, taking your foot off the long skinny pedal and she ran fine around town...

With everything you've already done, the time and miles on your rig, you may need to drop the tank and purge the that lurk in her fuel bag.

Probably not a bad idea at this mileage. I'll have to look into what that entails...

I'm wondering if bad grounds or vacuum lines could be an issue too? I'll have to give those another look in the mean time