got a F350 flatbed with a 351M its a 1980 but i figure the 73 to 79 forum would be more knowldgeable on this engine. It used to start and idle good, now it hardly idles. at any little bit of throttle you could hear the butterfly's open the air hiss as it promptly stall's, checked the timing chain it was good, it has almost 15 inches of vaccum and is steady, the distributer is on time at 10'BTC i am having trouble now getting my timing light to pick-up, i tried changing out my coil ( i had a msd blaster 3 i threw on it) didn't change it at all. I'm trying not to spend alot of money on this thing but i would like to have it running it makes a great around the barn yard truck!!! i know i'm probably overlooking the odvious so any help is appreciated... Thank you very much.
You could have a manifold vacuum leak.
Check the the vacuum line going to the brake booster and other vacuum lines which would keep it running and idling smoothly.
Maybe your truck is starved for fuel.
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.