I have a 99 accord, runs great but sometimes it just shuts off easy to start back

Replace the Ignition Control Module (ICM), located inside the distributor. Apply silicone heat transfer compound to the back of the new ICM. I recommend replacing ICMs every 120,000 miles or 10 years, whichever comes first. If you want, check for any codes and pending codes with an upscale scan tool.

99 accord shuts down going down the road

Typically, this is an intermittent ICM failure on Hondas. On late model domestic cars, intermittent MAF Sensor failure is frequently the culprit.