Truck struggling...bad injectors?

[RmGuY0708]

Alright, well i pulled a pontoon boat home last week that weighs maybe 4,000 pounds 125 miles to home with my '94 2500, auto, 3.73's, 241,000 miles. My truck was really struggling when I went over 45mph and smoked a whole lot. I can pull this with my F-150 with the 351 with hardly any effort. Also, my fuel mileage is about 15 mpg. Do you think this is all because of bad injectors?

Also for buying new ones, how can marine injectors give you better fuel mileage if they let more fuel flow into the cylinders?

[1999GMC]

ARe you sure the turbo is working. A lot of smoke is unburned fuel. Do you have a boost gauge? Check and make sure you have vacuum a the wastegate on the turbo, if no vacuum check the hose back to the solenoid.

[RmGuY0708]

yea i have boost and vacuum, the trucks even misses a little at start-up so i think im pretty convinced that this problem is injectors