1996 Ford Thunderbird 1996 Thunderbird Cracked Intake Manif

Hi, I have a 1996 Tbird V8 with 243000 miles on it, I bought it new. I'm having overheating problems and I'm pretty sure it's a cracked crossover passage on the plastic intake manifold. I haven't torn it down yet but steam comes from there behind the alternator, then the reservoir cap lets go and antifreeze pours out there. I've priced aftermarket replacement manifolds and they are quite expensive, especially with all the miles I have on the car. Do I have any alternatives other than replacing the manifold? Is there anything that will repair the old one? And I wonder if my cap is shot too. Any help would be appreciated.