Car bogging in rain

This has puzzled me- and this is sadly my last resort. I have a 96 pont Sunfire GT, and have spent 4,300 dollars in repairs- and about 2500 of that is because of this problem. My car will not run right in the rain, and only when it rains. It will start to bog out when its in neut- and then if I start to get going it will feel like it is not going anywhere even though I am pressin the peddle to the floor, and the rpms will rise but the car will not move and the all of a sudden it will go off like a bullet. But the stupidest thing of all is that this only happens when it rains- and any one that tells me its the coil packs and housing units is wrong- I have been through 4 of them american GM and not. I have replaced the fuel filter, the gas tank(had miner hole at top no big problem, didn't have too)the coil packs-spark plugs-housing unit-boots- and anything else connected to that 4 times, new computer, 7 map sensors, and the list goes on trust me.....So anybody that can help me- I don't think you would even know how much help it would be. I have an awsome mechanic now( a new one) that won't stop till he finds it- but I need even more help.

Its thunderstorms today- car is not running....reallly mad. I was 17 when I bought this car and it hasn't worked since day 1- nobody has heard fustrated like I have.