97 S-10 2WD 2.2L auto trans. 120k miles

This isn't a frequent occurance, but upon starting up it feels a little rough. Acceleration is very sluggish to about 30-40mph. At that speed it seems to run fine, but I can feel the engine sputter a bit. At hitting about 50mph, the truck just feels like I could floor it but it won't gain speed. At a stop the idle is very rough, and when off I can smell fuel, more towards the front drivers side. Recent new head, plugs/wire, air filter. Thinking injectors need to be replaced. Most other times truck runs fine, until I hit the 50mph mark (4 miles to work, thats about the extent of my travel, lots of lights) at 50 it just doesn't move. Thanks for looking at this!