Hard Starting

[DougR]

I have a 1990 525i 136km Over the last couple of months I am having a lot of problems starting it when warm or at usual operating temp.It grinds over for about 5 to 7 seconds before starting,if it dosent start I release the key and try again and it will start almost immediately.I have had the fuel filter changed,all vacuum leaks fixed,and done an injector clean.It starts perfectly when cold and after sitting overnight.Would really love some guidance as to what to do next.
Doug