Depends where you live im up in ottawa so winters werent nice to her. had to take the bed off im still in the process of finishing it up. all the bolts were seized to the bushing sleeve. orderd new poly ones
I have a similar problem with my 4.3 4l60e except it stays at 5k WOT in first. do you have a rough idle? couple people told me it might be the TPS. curious to see what fixes yours