When smog check was done it read two codes po 411 and po 420

Theres a vacuum line off under the throttle body when you removed the intake manifold it probably got pulled off also its very hard to see

Why would you change any items?

Have you not googled the code?

420 & 430 are exhaust converter issues

You change no parts,you check for codes & component
test system faults using the codes, until you find a problem

How do you know the pump is defective, what is the code?

you really need to drive it for min of 30 minutes before you go, they need time to heat up and run a cycle,

This is a common one and is usually just a sensor but could also require replacing the catalytic converter to correct. Nothing bad will happen if you let this one go except that you won't be able to pass a smog inspection if you have the error on. I would try resetting the error and see if it comes back.

You are probably right as all codes refer to misfire in cylinders.. have a compression test done to check for blown head gasket and cracked/warped head and have a cooling pressure test done also to show cracked head and other than head gasket.

You might try replacing the PCV valve. . .just a thought.

having PO 304 = Misfire cylinder 4,PO 306 = Misfire cylinder 6, as I read above you have done the most. The thing that you have missed is to check whether the Catalytic Converter is faulty or not. To get an idea check whether you have a smell like rotten eggs at the end of the exhaust,you start having problems with cat and needs replacement. My advice before you go for a cat replacement is good to visit an MOT center and check your emissions and then you decide,

this code indicates a missfire problem on cylinder #4,,this could be a bad plug,wire,injector,igntion module for cylinder 4,compression problems.that need to be checked out.

a po 1401 code is a egr code (code reads) DPFE sensor curcuit high voltage.most cases, i replace the DPFE sensor. this sensor is located on the side of the intake manifold .it has two vacuum lines going to the exhaust system ,or pipe. and it will have a gray plug going to it.this sensor is about 1/ 1/2 to 2inches wide and maybe and inch tall and a 1/2 inch thick. it takes a 7mm socket to remove. and all parts stores carry these for 40 50 bucks. good luck! and i would clear codes and see if both codes go away.