Toyota Repair: 1994 Camry - dies at idle, Hard hot start, camry xle, high mileage

Question
My son's 1994 Camry XLE 2.2L (5S-FE) with 186k miles has a problem which first started very intermittently about a year ago, but recently is getting much worse – and consistent.  First thing in the morning, or anytime it has been sitting for over an hour, the car starts and runs fine except for white smoke in exhaust until it warms up.  However, if you try to let it idle for a few minutes it will die.  He reports that just before it dies he hears a “pop”.  Then, hard hot start after it dies,  or if you just shut it off and try to restart in less than 30 mins it will act as though it is flooded, and takes many cranking cycles to start (if at all).  After it finally starts it runs poorly unless you shut it off and let sit for at least half an hour.  Took to a mechanic who said there was no fuel pressure, so they replaced the fuel pump and filter (to the tune of almost $500!), but did not fix the problem at all.  

Please help!  Is it possible an injector is not sealing properly, so it is flooding at idle?  Any other ideas?  Obviously with the age,  high mileage, and after just being burned on the fuel pump debacle I do not have much appetite to sink a lot of $$$ into this car – but he needs the transportation.  

Expert advice would be much appreciated!

Answer
Excessive white smoke(steam) from the tailpipe would be cause for cencern, there may be a headgasket problem and coolant may be getting into one or more of the cylinders, that's a possibility, some steam is normal when cold due to the condensation in the catalytic converter, as soon as the cat heats up the water is turned into the steam and sometimes water dripping from the tailpipe, this is normal.
So my question is, how bad is it steaming?
A small amount is ok, billowing is not.
If the engine was flooding there would be a lot of black smoke after it starts up, is that the case?
At this time I would recommend to have it checked for a possible blown headgasket before putting any more money into it that won't fix the real problem, whoever you took it to did not diagnose the problem correctly so I recommend paying the diagnostic fee at the toyota dealer(if possible)which is normally about $80-90 to at least find out what exactly the problem is then go from there.