suburban loss of power and vibration up hills
I own a 1999 GMC Suburban. It has 94,000 miles. For over a year now I have been getting a vibration that feels like when you drive a standard and you are in a higher gear for the speed you are driving but you have not pressed the clutch in yet. It has been happening for the past 12,000 miles off and on (like once or twice per month) but not enough to show the mechanic to figure it out. It seems to happen when fully loaded and under strain like a hill or from take off. I have also encountered a feeling of loss of power while driving 60 MPH up a hill (to the point of pulling over, stopping then starting from 0 again) the engine light does not come on nor does the tachometer jump around like the engine is stalling. The problem goes away as fast as it comes. Originally I replaced all the plugs and wires thinking the problem was caused by a misfire. I then replaced all four tires for the vibration. I drive away from the mechanics’ thinking we may have fixed the problem until I drive 1,000 miles and it pops up again. I am not sure if I am chasing two problems with the loss of power situation. I plan to take the truck on a 900-mile trip for Thanksgiving and have an appointment for Wednesday at the mechanics’.
Thanks for any opinions,