Theresa, Looks like Gramps always took it easy on your car, and it's got some dirty passageways and sensor in the intake, and pehaps an O2 sensor failed.
There may also be a CAT issue that caused all the rest. For instance, is there leaded gas anywhere around you that Gramps may have put in the tank? Leaded gas can accerate the clogging of the CAT, and damage the O2 sensor, then the restriction may force more exhaust crud into the EGR system, and make the MAF sensor there dirty.

Let's hope for the easy solutions. These may be DIY fix-ups. If you have auto maintenance experience, there's some guides in this forum to cleaning the MAF P0171 and 174. The 400s codes concern the EGR functions. There's also some guides to taking things apart to rifle out the goo that accumulates in the passageways and in the valve. The vacuum circuits also need to be inspected to see if they are not leaking. The 1100s codes concern the O2 sensor. There's techie ways to use a meter on the sensor to see if it's getting heater voltage and if it is responding to the gases in the exhaust.

So for a start... do you have a "car guy" friend or want to be a car girl yourself?

most of these codes don't involve getting new parts, just pulling the ones that are there and cleaning them. Granps musta' liked to go fast! like Gar said leaded fuel does this in a hurry. kinda like I envision your grandfather. mine went on a tractor in '75.

H80 DTC P0136 AND P0156 MONITOR DOWNSTREAM HO2S OUTPUT VOLTAGE FOR ACTIVITY. DTCs P1137, P1138, P1157 AND/OR P1158 INDICATE LACK OF HO2S SWITCHING
Note: Refer to the PCM connector pin numbers in the beginning of this pinpoint test.

Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any KOER HO2S DTCs.

DTC P0136, P1137 and P1138=HO2S-12
DTC P0156, P1157 and P1158=HO2S-22
Visually inspect for:
pinched, shorted, and corroded wiring and pins
crossed sensor wires
exhaust leaks
contaminated or damaged sensor

DC16 DTC P1100: CHECK MAF CIRCUIT FOR INTERMITTENT VOLTAGE TO PCM
Start engine and bring it to idle.
If a stable idle is not at least 700 rpm, GO to Section 3 , Symptom Charts.
Run throttle up to 1500 rpm for 5 seconds, and bring back to idle.
Access MAF PID (MAF V PID) while completing the following:
Lightly tap on MAF sensor and wiggle harness connector to simulate road shock.
Is MAF PID (MAF V PID) changing below the minimum 0.23 volt or above a maximum 4.60 volts (refer to Voltage to Mass Air Flow Conversion Table at beginning of this pinpoint test)?

HF1 DTCs P0420 OR P0430: CHECK FOR MISFIRE DETECTION MONITOR DTCS
NOTE 1: Be sure customer has not:

Refueled vehicle with leaded gasoline.
Noticed high vehicle oil consumption.
NOTE 2: If entering this Pinpoint Test for symptoms only, go immediately to HF5 .

NOTE 3: Internal deterioration of a catalytic converter is usually caused by abnormal engine operation upstream of the catalyst. Events that can produce higher than normal temperatures in the catalyst are particularly suspect. For example, misfiring can cause higher than normal catalyst operating temperatures.

Retrieve and record all Continuous Memory DTCs (MIL and non-MIL).

H41 DTCs P0171, P0172, P0174 AND P0175: FUEL SYSTEM AT THE CORRECTED FUEL TRIM
Note: It is necessary to address all Continuous Memory Ignition and Misfire DTCs, if received during Continuous Memory testing, before addressing any Fuel Trim DTCs.

DTCs HO2S Reference list:

HO2S-11 = DTCs P0171 and P0172
HO2S-21 = DTCs P0174 and P0175
Check intake air system for leaks, obstructions and damage.
Check air cleaner element, air cleaner housing for blockage.
Verify integrity of the PCV system.
Check for vacuum leaks.