M800 missing at cold start for about 1km.

Maruti 800 carb model experience missing (feels like fuel cut off while giving acceletrator) for about 1km after cold start. Then its running smooth without any problems. Replaced spark plugs, fuel filter, air filter, changed oil, cleaned distributor and tuned. If I stop the car more than 3/4hrs the problem reappears but not serious as after cold start.  If I cold start and leave it to idle for about 20 mins before moving, there is no problem. any problem with fuel pump? please help.

Check the carb

-especially the fuel jets(main and pilot).

Also check the Battery.  Was the Battery replaced/checked & recharged during recent refurbishing? Do check for "power leakage" and keep Battrery and its surrounding grime-free.  As the alternator charges the battery for sometime (as you drive/initial idling around 20 mins) the Battery may be performing at its best.  While you park the car overnight/for an hour, there might be very low power leak.

Battery was replaced only six months back and is in good condition. As Binoy suggested it may be the problem with carb. So, instead of manual carb cleaning I use this chance to try '3M Fuel Tank Additive' fuel system cleaner. It costed rs 250/- for 240ml for single use. I'll post the result later. Just trying to check if it can replace manual carb cleaning job. Any comments on 3M products?