What is this "too rich" error code of which you speak? The actual code number

 

Are we going to need to point out the difference in "Fuel TRIM system rich" and "fuel system rich"? I wish those reader programmers weren't so lazy. How much time do they save by deleting one word?
My bet is you need a EVAP purge valve or you have a leak somewhere between the MAF and the #1 O2 sensor. But, what do I know?

 

I knew when I wrote this someone would say this, hold on I’ll get my slippers on and go find the digits

 

Evap purge solenoid is 2 days old 😃
just a sec I’ll get the actual code #

 

Error code is p0172 fuel trim system rich

 

Also.. is there no inline fuel filter?
pvc valve?

 

No inline fuel filter
no pcv valve

as for the P0172 code , clean your MAF sensor

https://www.obd-codes.com/p0172

 

...and make sure you plug it back in.

P0172 means the ECU thinks the trim required to correct an initial rich a/f condition is excessive. I think that could mean either the injector orifices are too big or they're leaking. That would also explain the hard starting. Do you still have your original injectors from the original motor?

 

However, the fact that you can smell the excess gas fumes would mean that the sensors are wrong and needlessly dumping fuel in. I am slow to blame injectors and computers for every problem.
A vacuum leak between the MAF and #1 O2 sensor. Brake booster hose, anything connected to the intake manifold, air tube to throttle body, any tube made of rubber under the hood etc.
Bad MAF, Bosch O2 sensor, purge valve not hooked up tight.
One of the most overlooked points is the air tube to the TB, it cracks where the PCV tube connects or does not get tightened down. Another is the brake booster tube.

 

MAF is brand new