What do you think wrong with this truck?

[Down Deep]

I have a 2003 F-250 with a 5.4, 80,000 that Ibought new. Vehicle is mainly driven to work and I haul my mid-sized boat. A month ago I was driving up a steep hill and my "check gages" light came on and the engine went to 1000 RPM. The temp gage registered hot so I immediately pulled over and shut off the engine . I opened the hood and didn't notice any steam or overflow coming from the engine or radiator. I returned to the vehicle restarted and the gage registered dead center and ran fine. When I got it home I checked under the hood and noticed that the coolant tank was a bit low and topped it off with about 1/2 gallon. Since then I have driven the truck problem free until about a week ago when I noticed that the exhaust seemed to be putting out an excessive amount of white steam when I start it up. This lasts for about 5 minutes then clears. Vehicle runs fine and has plenty of power. There appears to be some coolant in the oil because I notice some milky white on my oil filler cap. It also lost about 1/4 of coolant since the last time I added it a month ago. I've had two mechanics look at it and one says cracked head the other said intake manifold gasket. One is a lot cheaper to fix than the other. I've got another appointment with a guy recommended by a local machine shop. My question is, how accurate can a good mechanic troubleshoot this problem without ripping the whole engine apart? Could their be another cause.

[Jeremy airjer W]

A little bit of milky oil on the oil cap is normal.

To see if there is a head gasket failure one of two tests can be done. The coolant can be sniffed with a four gas analyzer to see if there are hydrocarbons present. They can also use the bulb tester with the blue fluid. If it turns green there are hydrocarbons present.

If it passes either one of those than the cooling system can be pressure checked. Preferably with the engine cold, to see where the coolant is leaking from.