I know there are a ton of theards on modding the 351w. But this one I have a specific question. I have a 86 f150 regular cab long bed. Its got a 351 with the stock 4 barrel. It runs like a top and is pretty quick of the line but runs out of breath after 30 pretty much once the auto switch's into second. So what will help it pull a little more and last longer. Cam or shift kit or intake or headers

 

If it's got the stock exhaust on it now a set of longtube headers and exhaust will uncork so much power you will have to rejet the carb. I have seen this first hand.

 

knowing more about the truck would help also. large tires, gear ratio etc..

and what Conanski said