The downloads work 95% of the time, but then some of them fail for no apparent reason, and I get this error message back. After some short time, the downloads return to normal with the same OAuth account credentials. This is messing with my dataset.
403 error would typically happen after the account consumes all the available processing units/requests within the billing cycle. With monthly cycles the quota would be reset on 1st of the next month and account would continue to work.
What you are describing seems not consistent with the above, but we don’t have sufficient information to assess what might be the issues.
If I am not mistaken, your organisation has an Enterprise-level account, which means you can make use of our helpdesk.
I would suggest you provide as detailed information as possible:
which account specifically you are using (e-mail)
when you were noticing such 403 errors (time, what was the request you were trying to trigger, etc.)
if you can see some pattern, do describe this as well