sputters when accelerating at 60-70mpg on inclines

Hi, my name is Devin. I am an auto repair expert with the Car Genius team here at RepairPal. I'm sorry to hear you're having trouble with your Sierra 1500. The sputtering you're experiencing when accelerating at 60-70 mph on inclines could be related to several factors. One possibility is the engine might be struggling to get the power it needs at that RPM range, which could be due to issues like a clogged fuel filter, a failing fuel pump, or problems with the ignition system, such as spark plugs or coils. Another possibility could be related to the transmission. If it's not shifting correctly or if there's a transmission fluid issue, it can lead to a lack of power during acceleration. I recommend having a professional mechanic take a look to diagnose the issue properly. They can perform a diagnostic check to identify any fault codes that may give more insight into the problem. If you need more advice, have any other questions about your vehicle, or would like to get connected to a RepairPal Certified shop near you, we have you covered. Give us a call at 877-913-1554, and we will happily help you out!