Pontiac Repair: 1999 Pontiac Montana computer codes, fuel guage, emission control system

Question
Here's the problem....the van didn't start due to bad fuel
pump. Replaced fuel pump but still no dice. Checked the bundle connection behind drivers seat and under carpet. I believe it is c305. Replaced the 8 and 4 pin connectors. Van started. But prior to this the fuel level guage was not registering correct. Then the fuel guage goes to full then in 15 seconds pegs out at empty and stays there.
After a few weeks things started getting wierd. First, the ABS/TCS warning lights lit on and stays on. Then the LOW Coolant light went on. Then the check engine lights went on
and so a pulled the codes and here's what I got:::

P0102-MAF or VAF circuit low input
P0135-Oxygen sensor heater circuit malfunction (upstream         
     sensor no)
P1652-Electric cooling fan relay control circuit
P1676-Evaporative emission control system, purge valve
     solenoid control circuit

Please, if you can't guide me into at least what sensors or
circuits to check, say so.

Now here's what I did do/checked...on the MAF/VAF, I checked
the PINK wire going out from the sensor for 12volts...did not get 12 volts...got ZERO volts.
On the fan, only one of them worked and so I replaced the 5 pin RELAY and now both works altho they operate slowly and
not the FAST mode they operated before.
The TEMP Sensor was relaced also.

I have the talent to repair it if only I was given a heads up on just what to check. Anyone can advice to take it to a
repair shop..that's not any help for I need not go to ALLexpert to tell me that.
I have asked this same question at other sites only to be told to take it to a repair shop.
I'm the type of person that loves a challenge that's the way
I lived.
And please, each code mentioned above has a reason for it to send up a code.
All I'm asking is WHERE and WHAT to check for each code and
in specific, the fuel guage.
Please, meet me half way on this...it's very important to
me and my family. Money is very tight when you have 7 kids
that's why I can't afford to take it to a shop,being the sole money maker, but like I
said, I do have the tech know how but lack schematics and
insights.

Answer
Okay Jimmy:

Heres the deal as best as I can help you out. The abs/fuel gauge and fuel pump issues are more than likely all from that same connector in the floor pan. My guess is that this van has a water leak and that the water has contaminated that connector. also the evap system goes through that plug as well but but it controls the Vent solenoid by the tank and also the pressure sensor inside the tank. If those wires are corroded together especially the ones for the tank pressure sensor then it can cause other derivability issues. that sensor has a reference voltage sent from the ECM to it if for some reason that reference voltage is shorted to ground or has resistance to ground it will cause a bunch of issues. check that connector again both sides inside the van and the harness going out to the gas tank and abs wiring. As for the p0135 it could be a bad heater in the #1 sensor with the key on check for voltage on the pink wire engine side of the harness and ground on the black wire if you have both of them then more than likely it's a bad O2 sensor. as for the p0102 you should have battery voltage on that pink wire at the maf sensor if you don't the sensor is not going to work. check the fuses in the fuse box. As for the p1652 I just looked in my service information and that code doesn't show for a 99 Montana with a 3.4 V6. what I have seen on them is wiring issues along top of the radiator where the wiring loops around and into the box where the computer sits. I have seen the wiring rub on either the radiator attachment bracket or on the a/c lines that are right there. It may be a place to look for an issue and it may also be a source of you EVAP solenoid issue if it's not tied into the connector in the floor issue. This is really puzzeling to me you either have a bunch of small things going on here or one root probelm that's causing all of these issues. sorry I can't be of much more help then that. A real code reader and data scanner would help out with trying to see what's going on without throwing parts at this in hopes that you find the problem. Well Good luck and I hope I could at least help you out in some small way. :)