Engine stalling, erratic fuel gauge

Car started stalling out with any cause. Stalled out the other day and would not start. I the truck took it to a shop, shop said the fuel sending unit was not right, either not put it properly, or going bad. What I have read, the fuel sending unit will not make a car stall as long as there is gas in it. I picked it up from the shop, filled it up, and it stalled out within the quarter of a mile from the gas station to home. My question is, will the fuel sending unit make a car stall out, even at high speeds? It does stall while idling, and also while driving sometimes. Also, the fuel gauge was acting erratic for the first time today. Filled it up, fuel gauge dropped to empty, then shot back up to full.