Battery Dead problems of the 2008 Jeep Cherokee

I have a 2008 Jeep grand Cherokee diesel limited two wheel drive. I bought the vehicle with 92,289 miles. At 93,290 miles the check engine light came on which according to the Dodge dealership indicated that the eeg valve and battery was bad. So I replaced the gr valve in the battery. Periodically since then the check engine light would come on and then go off. On a trip to ohio the engine light came on and the car died on the freeway during a rainstorm. It was towed to a local Jeep dealership for diagnosis. The dealership told me that the airflow control valve was bad, but they needed to pull the battery out and disconnect the powertrain control module to get a true reading and make sure it was the airflow control valve. The powertrain control module is located underneath the battery. Upon pulling the battery and box the mechanic noted that there was battery acid on the power control module and on the wiring harness that connects to the power control module. I was told that in order to get proper readings the power train control module would have to be replaced as well as the engine wiring harness for a total cost of $2091. And they also indicated that after this was done they would be able to check to see if there were any other problem. I believe all the problems may have been false readings because battery acid had eaten through the powertrain control module and damaged the wiring harness connector, causing false readings when hooked up to the diagnostic machine. I do not have $3000 a month to invest in this vehicle to continue to find additional problems. Please help me!!!.