Hi. I have a 96 ranger w/2.3L, manual trans.
When I start the engine in the mornings when it is cool it sputters for a few seconds and then runs great and has plenty of power. Then when it warms up it is very sluggish with hardely no power. When I take off from a start it is like it hardly has the power to get going and sometimes it souds like it is backfiring, not out of the tailpipe though, from under the hood. I have changed the filters and my check engine light is not on. I have 250k miles on this truck and it has done this to some degree for the past few years getting worse every summer.
Thanks for your help

You're going to need to scan tool to see what the sensor are reading, they maybe within spec but not reading correctly. My guess is the O2 sensor but, that is only a guess. good luck

Is there any oil leaking from the head gasket or the valve covers?

Could be dirty injectors, you could try running some injector cleaner through it to see if that helps

Thanks for y'alls answers. No it is not leaking oil josser.