Engine Mechanical problem
1984 Ford F350 V8 Two Wheel Drive Manual unknow miles
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I can start cold, drive with no problem for 10-15 miles, but then the truck feels like it is running out of gas, it jumps repeatedly, then will quit running altogether. If i stop to let it cool off a while (10 minutes or so), it will restart and i can drive a little while (mile or 2) then the same thing happens. This has been happening since I ran out of fuel on my main tank and switched over to my aux tank. It does this on both tanks now.

In the morning (or after a long cool-down) it is again running just fine. For 10-15 miles or so.

I replaced the fuel pump (which was leaking) about 3 or 4 months ago.

What do you guys think is causing this behavior? Thanks in advance.