failed smog test on 1995 Ford Aerostar

my 4.0 aerostar has exsessive n. o. reading.i changed the mas sensor and the check engine lite is now out.what other repairs should i do before i retest it?

Asked by for the 1995 Ford Aerostar
1 answer 1 comment
the mass air flow controls hc and co. nox is controlled by egr and cat converter. you had more than one problem. have these 2 items checked for operation

Roy
thanks for your reply.i was hoping not to replace the cats as they are high dollar.ill change the egr and see what i get.if it still wont pass ill have to take it to the referee.