My 1990 stock Blazer started acting funny when the engine is cold. When cold the engine starts and idles fine and it will drive fine but when at a traffic lite and the light turns green and I give lite throttle she seems to hesitate and stumble. press the throttle harder she moves along. Sometimes as I'm accessing the freeway on ramp she seems to totally cut out but when I press the throttle more the truck runs ok. I replaced the fuel filter a while ago, new MSD plug wires, rotor, and cap. I have noticed that this problem only occurs when the truck is cold. It runs fine when hot any ideas? BTW there are no codes in the ECM, code reader shows nothing unusual that I can see. Any help would be appreciated. Dan..