Hey guys I'm working on my father in laws truck

Ok here is the story about a month ago his 07 f150 overheated on him right in front of some guys shop so he pulled it in guy looked at it told him he needed new water pump thermostat an fan clutch. him not know much about vehicles let the guy go ahead an do it well a day or so goes by an he calls me an says while he was driving the air will go cold an then over heat so my initial guess is air pocket so I then went over to his house pulled truck up on an incline pulled cap off an ran rpm at about 1500 an could feel it start running rough so let off of throttle an it let out a huge pocket so we then drove it down the road an heat was working fine an everything next thing you know it blows cold an over heats so we take back an I have him running the throttle at round 1500 an when air pocket comes out I see specks in the coolant an I am certain it is oil so I worry head gasket but he did have coolant flush to so not sure if he may have severe clog in heater core an just got specks from overheating to frequent not confident but also I'm not to common with fords iv always been a GM man an have heard that fords are notorious for cooling issues
BTW. I did check thermostat an went ahead an put another new one in still overheating at random

 

Sounds like a head gasket to me. Combustion gasses are getting into the cooling system causing the air pockets. I bet the coolant smells funny. Take the t-stat out until you can get it fixed properly. Stop leak is only temporary at best. Removing the tstat will prevent air pockets in the engine.

 

I plan on doing a carbon test this weekend thank you for your post
Best regards Tanner