Explorer gets hot and gags under load!

My 97 Explorer Eddie Bauer V8 has a summer problem while pulling a ten
foot Jayco Pop-up trailer. The car runs fine up to the point where I
start up a long hill with outside temps of 90 plus then the engine
gags and almost dies. I can floor it and it misses and cuts out but
still accelerates. It will keep stuttering even after the road
flattens out once it starts. Usually the next morning it's back to
normal. It never totally stalls or dies but runs in fits. I think the
high temps have something to do with it cause I ran the same rig up
the 9000 foot pass outside of Jackson Hole and not miss a beat,
however the outside temp is only 60 degrees. I have been having this
problem for several years and have even taken it to a dealer while in
the throes of this behavior. He thought it was the fuel pump but it's
been running ok for years since. I checked the MAF sensor, replaced
all 4 O2 sensors and the gas cap. I have heard about ignition pack
failure due to high temps and fuel pressure valves and fuel pump
relays. Anybody else have these symptoms and solutions? Summers
coming!
Thanks for any help!
Scott Harrison

I dont' know where you're at, but I'm in Texas and summer's been here for a couple of months now. Over 90 every day!!! Anyway, back to your problem...that's a tough one. You're probably gonna have to replace the fuel pump to eliminate it as a culprit. If it fixes it, great. If not, then on to something else. Intermittent problems are the worst to diagnose since you don't have a hard failure to troubleshoot and find the bad component. You might take it to an auto parts store and ask them to extract the codes, if any are there. Could give you a clue to what's the cause.