COLD START IDLE

Hello,

I have a 1987 volovo 740 GLE Wagon-noturbo / 4 cyc. When the vehicle is started in the morning on a cold start it stalls unless it is warmed for 5 minutes.
I replaced the plugs with (Boschplatinum)which seemed to help. The previous plugs had a blackness to the porcelain.

I have not replaced the fuel filter and a full
tuneup was done 10K miles prevoius. Car has
142,000 miles and has been well maintained (air filter Ok) throttle body was cleaned with spray and fuel system cleaner added to the tank.

thanks

Steve