My engine wont start for days, then starts?

First thing to do is to verify that the engine isn't getting fuel after it cuts off. Check for a spark at one of the spark plug wires after it cuts off and will not restart. (Ignition problems can cause these same symptoms).
If there is not spark let me know and I will post info on how to diagnose the ignition system.

In order to check for a spark at one of the spark plug wires, remove the spark plug wire from the spark plug. Connect it to a spark tester and connect the other end of the spark tester to a good engine ground (a bolt will do fine). Have an assistant to crank the engine and you should see a spark jump the gap in the spark tester. If so, the ignition system is doing its' job. If not more testing f the ignition system is required.
If a spark tester is not available, remove the spark plug wire from the spark plug and lay it (horizontally) on a metal part of the engine. Have an assistant to crank the engine and you should see a spark jump from the end of the spark plug wire to the metal engine surface.

Also, if you suspect that it's not getting fuel, spray some carb cleaner into the intake manifold and then try to to start the engine. If it starts (or tries to start) and then dies, the problem is that it isn't getting gas for some reason, then we'll diagnose the fuel system.
As it is, since you've repalced a couple of part in the fule system, check for a fuel or relay loose fit in it's socket. Loose connections here could cause iintermittent problems. Also check fuel pump connection at tankif possible.

Scan for codes, and check fuel pressure with a gauge auto parts rent them fp lshould be 52-59 psi

The gray wire is the hot wire to pump. Those two codes you have deal with the evap and fuel tank pressure sensor. A pro really needs to diagnose the fuel tank sensor unless ther e is no voltage going to the sensor. Check the gray/blk wire to see if you have a 5 volt reference signal. If not it's ahort or connection problem but a pro should really check this as it could be the pressure sender.

Why are you worried about compression? Just scan and check fuel pressure not engine compression. If you are really worried about compression as long as it's above 90 psi per cylinder and within 20%of each other don't worry about it.

There is no code 306is it a 300? If it is have a pro check it as these are very hard to diagnose the problem

306 is amode 6 code.102 is a maf code, but should also be checked by a pro

Well the trouble is that the codes that you need to clear are very very hard for even a mechanic to figure out and you need apro style scanner because it can do stuff that the one at auto parts cannot that is why I told you to go to a pro. It can read real time stuff whereas yours cannot and a lot of those codes need that in order to figure out the problem. Sorry

Welcome to the forum, is the theft/security lite on the dash, on or flashing, when you try to start?