hey guys, i have a 1988 n/a. it has new plugs and finally got it running good, and have been driving it everyday! the fuel pump went out so i got a new gas tank and swapped to a walbro 255 and have been driving with that for about a week, its been doing great and then yesterday after noon i blew out an old fuel line so i fixed that with some new line and a new fuel filter just to do it while i was there. got in the car and started it right up and ran great on my way to work this morning, on my way to work (about 6 or 7 miles into my 8 mile drive) it started to cut out at regular driving. like perfectly fine then out, basically like stepping on the clutch, then when it dropped down in rpms it would be fine then try and give it gas to go it cuts out again. if i pushed in the clutch or put it in neutral and tryed to free rev it it would rev then cut out or if i did it slow it would rev to about 3k then out. i pulled over to the side of the road and the car stalled out, i went to start it back up and it fired up and ran fine, but it was blowing quite a bit of white smoke then it went away after alittle. i drove it 2 or so miles fine. got out of work and drove about the same distance back home (6 or 7 miles) and the cutting out came back. keep in mind that the car is running great before this happens, i shut the car off and started it back up and boom its fine again.... what could this be??? it came out of nowhere and i need the car for work, any help will be appreciated!!!!!

thanks,
Frank