Q: What can I check beside leaks,spark plugs,coils and connectors on 1999 Ford Expedition

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
Checked with a Valve Guage Tester and read Late Ingition Timing
I have checked for leaks
Coil on plugs good
Put new spark plugs
(1) Answer
(2) Comments
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