Zerotohundred

my prob is the engine unstable after general overhaul since it is ok b4 overhaul
at 1st engine can start but unstable n later on the distributor coil damaged

after replaced the coil, engine can start but still unstable, then timing belt was checked n then found that 1 teeth mistake. after done timing belt, then the engine can start n this time better than before but still unstable

all sensor was inspected and in good condition, no check engine lamp

what is the prob?can anyone who...