Hard start problem

Hi everyone .

i have a 1999 toyota corrolla for EFI 5A engine. it starts well in the morning but when i drive and stop for 30minutes or more it cranks more before starting.

once it starts it runs ok. if i turn off and on no hard start.... but if left for long cranks more !!

The exhaust has black suit and plugs gets black suit also. it does not consume oil, changed air cleaner and plugs also

any one with an idea