How long can I go with a bad Intake Manifold Gaskets?

I have a Ford Explorer 1996 V6 162, 300 miles. I have been having a stalling problem for alittle over a year now.My car's idle will go very low and stall. I can get it started sometime if i press the gas really hard. Most times i have to wait awhile to start it up. It stalls in nice weather and also if I stop alot of places and constantly turning the car on and off. So, to get the stalling problem fixed I have had a tune-up, new catalyic converter,(needed for emission as well but also could have been reason for stalling) new oxgen sensors, fuel regulator, tranmisson flushed, always have oil changes, new water pump, raditor.. lots more. Still noone has found out the real reason for the stalling problem. all mechanic says my car is fine. But when i went to my regular shop the one guy told me i needed a intake manifold gasket. So i brung my car in for the repair. I goes to pick it up and now the owner says i didnt need a intake manifold my car was fine?!!!!STRANGE!!! Instead he fixed other small thing. So after trying other mechanics with still no real help i finally went to the dealership. they told me I needed these items INTAKE MANIFOLD GAKSETS , PCV TUBE AND VALAVE , IAC VALVE , BOTH 02 SENSORS , PCM REPROGRAM..okay notice i said one person said i needed a intake manifold gaskets but turned out I didnt?! I think they were trying to get my money. Another thing that one guy who told me the truth about my car doesnt work there anymore. I just spend so much money on my Ford Explorer already I really need to wait atleast another month to save to get these things fixed. Does Anyone Know how long my car can last until I get it fixed. Thats the only problem so far with the truck. My car has 162,300 miles. And also What do you think about my whole stressful car problem?