Cooling issue

I have spent the past 5 days searching forums so please don't flame me.

Here's the problem:

Did an Explorer upper/lower swap. Also put in a new Tstat. Had a 140 tstat (ran very rich) in there so I put in a new 180 (mr gasket).

Also upgraded to a contour fan while the car was down.

SO, after the car runs for about 20-25 mins bubbling coolant gets pushed back into the overflow. And if I keep the car on it gets violent and coolant makes noises. During the first 5-10 mins I keep the rad cap off and coolant is flowing. Also after it cooled down ALL of the coolant in the overflow tank was sucked back into the radiator. Leak?

So I put a pressure tester on today and its holding at 16 PSI (been on for 20 mins now). No coolant in the oil as well. At least not on the dipstick. Keep in mind the car ran very cool with the 140 tstat and did not have any overflow problems before I swapped all this out. Should I run the car with the pressure tester on?

I'm thinking I have a HUGE air pocket, bad hose somewhere, or some coolant passages are blocked and I need to flush it.

I tried to burp it but I can't run it for longer than 30 mins.

I think I need to do a cylinder compression check next. The car/engine only has 65K miles on it and runs fine so I HOPE its not a head gasket.

Any ideas?

Yup forgot to add that I replaced the radiator cap too.

Yea I didn't even know they made 140's either, but that's what the previous owner told me.

Edit:

Just let the car idle for 25mins with the pressure tester on. Pressure went up to 26 lbs before I shut it off.

Did a block test. fluid stayed blue so hopefully its not a head gasket. I'm gonna get the coolant flushed this week and hopefully they can burp it the right way. If that does not work I'll redo the intake gaskets.

Problem solved. I put a big funnel in it and let it run for a while. worked like a charm.

Thanks guys