Intermittent - What a pain in the old you know where

[mr-natural]

58 Corvette with L98 engine: Running great for months, then died one time 5 miles from home a week ago, and immediately restarted - drove home with no problem. Four day ago about 5 miles from home started coughing through the intake and sputtering (just like earlier) - eventually died after turning around to head back home. Waited 40 minutes restarted but hardly ran - called tow truck - embarrassing. Once home the car restarted - barely running but noted small amount of white smoke from left exhaust. Engine has been using oil but normally I don't see any smoke. Never any codes were thrown. Yesterday reset lifters from one turn past zero to 3/4 turn. Vacuum is good at 15 - 17". Checked compression and it was all around 120-130 PSI. #5 & 7 spark plugs are just a bit darker than all the others. Did coolant pressure check and it was good. Started and it was smooth and solid - went for test ride and performed well. Stopped at a neighbors about 300 yards from home - spent maybe 3 hours - went to drive back home and barely made it back. Engine would either run right for a few seconds and then start sputtering and backfiring. Thankfully it ran strong for a few seconds to get me up my driveway and into the garage. Still no codes thrown. Suggestions please.