Q: Sudden Reduced Power when running fine - stop, restart, all is fine - what's wrong?

Hi there - first thing to check when experiencing a Reduced Power Light condition is for any problem codes that might still remain, even if the Check Engine light is not on now. There are several possible causes - an overheating condition, which would have been evident on your coolant temp gauge. A malfunction of the throttle position sensor, even if temporary, can cause this scenario. The TPS has a dual-measurement system for redundancy if one or the other fails. If engine management senses a difference in readings between the two - it goes to Reduced Power mode. Restarting the truck would have cleared it as long as no permanent condition existing. I would recommend a Reduced Power malfunction inspection. This inspection will check out the components most likely to invoke this condition. A mobile, professional mechanic, such as one from YourMechanic, will come to your location, diagnose this problem, give you an accurate assessment of damage and cost estimate for repairs