1993 Nissan 240SX 93 Nissan 240SX smog check help

THis is what we did last night:

1) We tried to remove the EGR valve entirely, but we don't know exactly how. Basically, we just removed the EGR valve vacuum hose and spray some Pryroil Carb&Choke Cleaner in it. We also sticked out finger in the bottom of the EGR valve and lift up the diaphragm while the engine is running. The engine stumbled, so we believe the EGR valve is working. Is there a easy way to remove the EGR valve from the car entirely? I want to clean the inside parts of the EGR valve. What nuts do I have to remove first? And what other parts do I have to remove first?

2) Then we seafoamed the car. We followed his steps:

33% gas tank, 33% crankcase. 33% intake manifold through brake booster line. I have a question here. Why the brake booster line will connect to the intake manifold? What is the purpose? And why there are other vacuum lines connect to the intake manifold?

Compare with other cars on youtube, my car doesn't have alot of smog coming out from the exhaust. Do we need to pour one more bottle of Seaform? If we decided to pour 1/2 bottle to intake manifold and 1/2 bottle to gas tank, do we have to do oil change and change the oil filter again? My friend said we don't have to change the oil and oil filter, but I argued that the seafoam will make the engine oil thinning. So, changing the oil and oil filter is needed after each seafoam regardless where we pour into.

That is all we did.

3) "ok, do this, add a bottle of isopropyl alcohol to about a half filled gas tank, drive it around a bit to get it mixed and in the fuel line. Alcohol lowers combustion temperatures thus NOx levels will be lower. Also, nox resolved from running lean which is one of the symptoms. Get the highest percent isopropyl alcohol and try again, get around 90% because the other 10 percent is water, though water is not combustable, it will dilute enough to not cause any harm. Also, try retarding your timing a few degrees. That may help. These are just cheap/money free possibilities. The alcohol wont hurt your engine, just dont use more than 1 bottle. About 16 ounces

Let me know if this works for you. I bet it will. Pm me or something"

Do you thing pouring alcohol in the gas tank will help emission?

Thanks!

1) Will high octane gas and octane booster help emission in my case?

2) Will retard ignition time help emission? How does it work? And how do I adjust the timing?

Thanks!