Head Gasket Problems?

My daughter has a 2000 explorer xls and she is having problems that a mechanic says is probably her head gasket. This is what has been going on and what has been done to her car,

They did a tune up and that is when the problems started. Her engine light keeps coming on and off - it jerks when she first starts driving - it is missfiring- her coolant is going down.They have done this - changed pugs - changed something my daughter called a motor computer - cooler wrap - put the explorer on the computer and it showed a miss fire but they can not find it. They told her it is probably the head gasket but it would cost a lot to fix that and they would have to do a lot to check it. She is a single mom going to school and working and does not have $2000-$3000 to put into this car. I read that you can check to see if it is a head gasket by getting the coolant anaylized and if there is hydrocarbons present it may be the head gasket. Also you could check the color of the oil and if it is a light brown or tan color it means that water is mixing with the oil and that also points to head gasket. Does anyone have any ideas on what the problem could be and is it sounds like head gasket? With the reading I have done most people have problems with the car overheating and she has not had any problem with that. Thanks for anyone that can help

I think she needs a new mechanic. You are correct, there are tests to determine whether or not a head gasket is bad. GUESSING is not one of them. For them to say it is “probably” a head gasket is pretty lame, and not confidence-inspiring.

The coolant level dropping is not a good sign, but it could be a leak somewhere other than the head gasket. How much coolant is being lost? What does the oil look like? Is it tan or milky looking?