Car starting problems when hot

The car is a 318i M43 motor, 1993DEC

Car was running ok for a few days after getting tuned by bmw to work after some mechanical work, that needed more expertise

The car will start first thing in the morning.

If I try to start it at noon it won't start

In the afternoon good chance it will

I was thinking that the fuel injecter seals may need replacing,

But I haven't asked anyone with mechanical know how of this problem

any suggestions I could try

thanks in advance