what the duce..?

[Brown_Eminence]

hi yall im new here :
ive had my b4000 for 7/8 yrs & she's always served me fine.!
just recently i had (had) a dead battery & replaced it w/ a $130.00 batt, and now she runs like "sh*t" i mean she'll crank up & run just sooo pretty...& quite but as soon as she's under load ( in gear ) she'll bog down & rpm's will go from 2500 or so to
dead "0" in a blink of an eye..(now) a little background on me. i was rasied working on engines & such..so im prudy knowledgeable. (but?) in this instance.?
" im perplexed"

* if you've got any ideas.? hollar @ me
thanks yall.!

 

[Curious Hound]

Nice truck! Is the CEL on? Any diagnostic codes? Make sure all the battery connections are clean and tight. Are you sure the alternator is good? What is battery voltage after it's been running for 5 minutes or more?