Sorry for the lack of information. It's a 2009 I4 with 81k (that I purchased used about a year ago) and all grounds are good. This all started when I replaced the positive battery terminal. The original one actually corroded pretty much off the battery. I replaced it with the same type (metal) and it started corroding again so I replaced that terminal with a lead one and this started happening.
I think you pin-pointed your own problem - if the problems started after replacing the positive terminal - that's where the problem is.
I believe your positive terminal is loose and/or has a bad connection - either at the battery or to the cable. When you drive, the vibration is causing a disconnection with your battery. This is bad for your electrical system since my understanding is that the battery serves to smooth out the DC voltage when the car is running. In addition, the connection may be good enough for a small load, but will not be able to pass a larger load - such as when the compressor comes on. I just saw this problem with a loose positive connection - lights & all worked but unable to start car.
How are you replacing the battery terminal - just a screw type pressure fit? Or a crimped/soldered connection - crimped/soldered is a lot more reliable, or just replace the whole cable - more $.
From what I read on the web, the corrosion is caused by a crack around your positive battery terminal & acid vapor corroding your connector - you should replace your battery. If the previous terminal worked (metal), I'd suggest go back to that if the lead one is causing problems. Use some dielectric grease on the terminal before connecting and spray with battery terminal spray to help with corrosion problems.