Where do you start looking for the problem if an 89 Accord with 190 thousand miles emits NO compounds at double what will pass?

1) clogged EGR ports--might have to be cleaned 2) check engine timing is in spec 3) make sure car is not overheating 4) catalytic converter 1) clogged EGR ports--might have to be cleaned 2) check engine timing is in spec 3) make sure car is not overheating 4) catalytic converter