I have a 91 302 with 120k I run regular gas no CE light and it pings bad

 

Engine running hot, quality of fuel are two issues I can think of.

 

The temp gauge goes over to the L in normal then back to 12:00 when thermostat opens…not sure what temp the thermostats is tho. It has done it for about the past 5,000 miles

 

Check and clean the EGR valve. A good seafoam treatment wouldn't hurt either. Also just because the CEL isn't on dosen't mean there isn't a problem they will throw codes without light coming on. If you don't have a code reader there is a sticky on how to use the jumper method.

 

The EGR valve and sensor are brand new

 

Yea that's not normal.

 

What should the gauge do? Running hot would make sense because it is a lot worse when the bed is loaded with oak

 

Timing?

 

It should go to where it always sits and never move until you turn off the truck.

 

i talking with my dad(he owned the truck before me) it has a small anti-freeze leak coming from above the transmission so he added a tube of stuff the radiator that didn't work so he added another. Ill flush the radiator and see if that changes. would you change the thermostat? whats the best way to flush the radiator? where could the anti freeze leak be coming from?