99 burb engine surge

I have a 99 burb that between 52 60 MPH will surge. the rpms will surge 200 rpms up and down, but not at any other speed. Not sure what to check for.:shakehead

Make sure you tune up is good.
What mileage and what engine?
When was last tune up
Any check engie lights?
How is the fuel pressure?

The motor is a 5.7 with about 155,00 miles on it. wires are good, plugs are about 2,000 miles old. haven't checked fuel pressure but previous owner said it was replaced at about 100,000 miles. no engines codes at this time:grinyes:

The motor is a 5.7 with about 155,00 miles on it. wires are good, plugs are about 2,000 miles old. haven't checked fuel pressure but previous owner said it was replaced at about 100,000 miles. no engines codes at this time:dunno:

The motor is a 5.7 with about 155,00 miles on it. wires are good, plugs are about 2,000 miles old. haven't checked fuel pressure but previous owner said it was replaced at about 100,000 miles. no engines codes at this time:dunno:

A 200 rpm surge may be TCC kicking off/on and off.
Make sure no engine running problems.
Get a good engine transmission scanner on it and check engine running and transmission shifting and tcc convertor circuits.
Also check transmission filter and fluid and service.
MT