I took to the mechanic recently and told me it was air suction was lose stop for a week and then start again same problem
Have your alternator tested. It sounds like it is not putting out enough amperage. The lights would flicker if the alternator is not putting out enough power by itself to run all accessories and you are pulling voltage from the battery. This will have a side effect of the battery not being fully charged when you go to start the vehicle the next time, which will make it crank slower and thus take longer to start.
I think you should check all the ground or bonding cables (battery to body, battery to engine, engine to body - whichever ones you have) as if one is broken it could cause the flickering symptoms you mention - leading to stalling, poor battery charging and maybe a damaged alternator.