engine missfireing and smoke from exhaust

[Krowzer1139]

well the truck just got a new marshell rebuld engine and its got about 15k miles on it and its worked fine all of a sudden yesterday after i got done at my first job i tried starting it and it wouldnt fire the second time it started but it was misfireing bad the engine was shaking the whole car i drove it to my second job and all the sparks are good but cylinder 4's plug was caked black so i replaced it right there and it still had the same problum i went behind the truck and its smokeing white out the exhaust. i just put new plugs new wires and new cap and rotor the coil is a blaster. im not sure where next to look does anyone have any advice to help me fix it or what might be wrong? there is a warrenty but its not very good. oh my distributer is advance 12 deg and i have a hyper tech chip. i was running 89 octane and motorcraft .44 gap firewire planum plugs with hayes 8.2mm wires and msd blaster coil

 

[sjr53]

Sounds like when my 86 suddenly went bad late last fall. I let it sit all winter only to find out is was just a failed fuel pressure regulator. Lots of fuel was being drawn into the vacuum line. When my 88 had a bad FPR, it was much less severe with just being a little hard to restart and idling poorly.

 

[Krowzer1139]

that was it thank you so much it had a had time starting at first but when it did it smoothed out after 15 or so seconds and there is no misfire or white smoke.

 

[IMenriched]

that was it thank you so much it had a had time starting at first but when it did it smoothed out after 15 or so seconds and there is no misfire or white smoke.

Keep a eye on your coolant level.