2000 Xterra extended crank to start

[kstone13]

I recently bought a 2000 Xterra with 153000 miles on it that has recently developed an extended crank-to-start problem that seems to be getting worse. I have to crank it for a few seconds to get it to start and when it does start it seems like its struggling to start. Once it gets started it is totally fine, everything seems normal. A buddy of mine said it could be an air intake problem, but the air filter was replaced recently and looks totally fine. I'm wondering if it could be something wrong with the egr system because it also failed its emissions test (I live in colorado). It failed on NOx reading 2.5 and the limit is 1.5. Everything else was way under the limit. I took it to a shop and they told me 2 of the 4 catalytic converters needed to be replaced, but that makes no sense since the hydrocarbons were way under the limit. I had read online that the egr system could cause both of these problems if it was clogged or a valve was broken or something (egr hasn't been cleaned in the last 5 years). A couple additional things, I think it struggles to accelerate on hills and it might have high fuel consumption (I can't say for sure because I bought the car very recently and I could be wrong about both of those). Lastly has 1 code PO325 knock sensor which is a generic knock sensor malfunction code which I think could be related to the egr system if the egr system is failing and causing an improper air and fuel mixture. So I'm wondering what you guys think about this. Could I be right in that it could be the egr or am I grasping at straws hoping I don't have to replace 2 catalytic converters?

[Trevor]

Before you replace any components I would run cleaning chemicals through the fuel and take for a long hard run to see if things improve.
Once the engine temperature is hot and the revs are high enough then it should make a difference next time you start up