EGR Vlave for 91 Voyager

Can anyone tell me if there is an EGR valve on the 3.3L engine used in the 1991 Voyager? I've recently failed my emissions tests for high NOx. Figured it might be the EGR valve. But, I don't see an EGR valve anywhere on this engine. If not equipped with an ERG valve, any ideas on why the NOx is high? Replaced the catalytic converter about 4 years ago. I currently have 200,000+ miles on the van. What about the O2 sensor? Thanks.