Advice NeededTLDR - Spend an additional $30k now to upgrade the sewer system on-site while the contractor is already mobilized or go with a sewer injection pump which is likely a viable solution the will last for years with proper maintenance. 

It is the local REIA and there is a multi-family meet up once a month (in addition to other niche meetings).

I would suggest you start getting some legal representation and then talk to the previous owner. 

Beach, I would also suggest that you schedule an inspector or some sort of third party.

So, I thought I should sell, take the profits and put into high interest account, rent a room for myself for about $1100 per month with all utilities included and that way I can save additional funds for a year.

What suggestions do you have about it?

Second I would suggest you come by for a weekend and drive the city street by street and just take notes.

This can give you the opportunity to possibly add more units within an existing property or even build additional units in the future. 

The building was completely transformed over the next year and a half including a new addition to How did you finance this deal?

Revenue is not profit though...you have additional expenses in STR (close to 50% of OpEx) due to cleaning, vacancy, and supplies.