99 Tahoe shudder starts at 70 mph

99 Tahoe 2dr 5.7 shudder starts at 70 mph. Runs and idles great but at 70+ i get a shudder that comes and goes. Once and a while it will set a P0300 code but does not seem to be misfiring. I did a all Delco tune up cap rotor wires plugs new coil and ing module. Fuel pressure test all good.
Full throttle runs great no miss. Any ideas.

99 Tahoe 2dr 5.7 shudder starts at 70 mph. Runs and idles great but at 70+ i get a shudder that comes and goes. Once and a while it will set a P0300 code but does not seem to be misfiring. I did a all Delco tune up cap rotor wires plugs new coil and ing module. Fuel pressure test all good.
Full throttle runs great no miss. Any ideas.

check the distributor shaft/rotor for wobble . over 170,000mi these usually start to wear.

Thanks J Cat, I was wondering if that would cause the problem. Should I go with any particular brand or just go to autozone.

Thanks J Cat, I was wondering if that would cause the problem. Should I go with any particular brand or just go to autozone.

go with the best warranty/price.