Car hesitates on highway than clears itself it almost like bad gas but has alot of work done

GM had a technical service bulletin 05-06-04-058 which had to do with a kind of chugging or loading uo under light acceleration. It would not set any codes in the computer. The most common finding was the throttle positing sensor being faulty and the tech will test it before replacing it.

There was a recall on these cars due to a problem where th engine would backfire and crack in the upper intake manifold. This was a fire hazard not to mention it could cause a driveability problem. It would create a vacuum leak which affects the MAP (MANIFOLD ABSOLUTE PRESSURE) sensor.
This relates to fuel mixture and would be noticeable at low speeds and idle.
Whether GM would still cover cracked manifolds after 15 years is debateable. The recall notice number is :97-C-02. This may get you started in the general direction.











gm had a warranty