What can I check beside leaks,spark plugs,coils and connectors

Did a tune up. Started to run with a rough idle and smoking Was not doing this before tune up Rechecked everything to make sure So checked with a gauge and it read LATE INGITION TIMING Also no codes have come out So trying to find out what has caused this It also wants to stall

try dis connect battery for a few minutes. comp. should go to default. might help.