I have 91 f250, 351, 137k, manaul. I was hauling up long hill, couldn't get it over25 mph. When I got to the top of hill looked under truck to see my cat was glowing red hot. I got it home but it wouldn't go over 25 unless down hill. I realize its an older truck and it never had the spunk it should have but now its just about undriveable. Any suggestions? These are some of the things i've replaced since Ive owned it: altenator, egr valve, water pump and just put a new cat on last week. Please help. This is my only work truck, I use daily.

 

oh yeah. i put new fuel pumps on as well less then a year ago. and no check engine light

 

You didn't mention anything about replacing the fuel filter.
When was that changed last?

 

MAP sensor,I betcha....hope your Cat's still good.It's getting too much gas/air mix.

 

Did fuel filter about year ago. before pumps