Egine runs perfect on a cold start

[explorerdogg]

Egine runs perfect on a cold start once it warms up trucks pulls slow

after about 10 mins of driving my engine doesnt pull as hard it acts if something holding it back it also knocks sometime, it only does this when the engine is warm the engine is not overheated its just once it get to a normal temp it starts to lag im running 93 octane gas, Any clue to what this maybe would be appreciated, I tried reseting the computer nogo,

its a 97 xlt 5.0

Thanks in Advance

 

[rjc]

First check/replace your air filter. Your EGR valve may be stuck open. rc

 

[explorerdogg]

what is a EGR valve and how do I fix it

 

[TPLYNCH]

Exhaust Gas Recirculation. Search EGR and you will find lots of threads about it.