There is an error message that displays on the dash for myself and thousands of others who own gmc/chevy trucks with these motors. they have a defective throttle position sensor with the truck where it says "reduced engine power". i've found 2 technical service bulletins that somewhat address the issue, but many people take their trucks to mechanics and dealerships to get the issue fixed and spend thousands of dollars in repairs and troubleshooting to get the issue resolved, to no avail. the 2 technical service bulletins that i found were #pip3089b (dated 10/31/2006) and #pip3042a (dated 8/30/2004). i've seen on many many forum posts about this issue and possible fixes, which when i read deeper into them, seem to not be true fixes.