I have the same problem as you described.

My Iriz has a unique (I think) problem. Occasionally, it takes a long crank to start. I would either have to keep cranking for a few seconds or stop and try a second time, and each time the engine will slowly come to life. This does not usually start from a cold start i.e. at home, but on the journey back home i.e. in a shopping mall or roadside parking. Two Proton shops have struggled to figure it out, one of them cleaned out the throttle body (what is this) and it seemed to help but the problem came back (I'm not sure that it helped in the first place). He has since suggested that I change my battery since the Century battery model that I have is 350cca (?) but the standard Proton is 430cca. Really need help on this!

Could be battery as you're never sure how long the car has been sitting in a yard before being prepared for you.

I always thought it is an Iriz known issue as it has been happening in my 2014 unit. Every time before a cold start, I'll switch it to ACC, pump the fuel a few times before crank to start...usually works