Potential fixes listed:
New battery - Will test today but I think it is fine.
Spark Plugs - About 5 bucks each for Iridium. Pretty sure that is what I used at around 80K miles. At 135K now.
New Fuel Pump - $78 - 494
New Fuel Filter - Not on RockAuto?
New Starter - $88 - 150 after core charge
New Fuel Pressure Sensor - $175
Someone posted this:
https://www.mazda3club.com/mazda-servic ... ems-55478/
1. Check fuel hold pressure after turning the engine OFF for 5 minutes or longer. Refer to Workshop Manual (section 01-14 FUEL LINE PRESSURE INSPECTION). Specification is 36.2 psi or more.
If below specification, check fuel line for clogging. If fuel line is clear, replace fuel pump according to Workshop Manual (section 01-14 FUEL PUMP UNIT REMOVAL/INSTALLATION).
If fuel hold pressure is okay, check spark plugs for fouling.
If fouled, replace spark plugs with modified plugs.
If not fouled, perform normal diagnostics according to Workshop Manual (section 01-03 NO.4 HARD TO START/LONG CRANK/ERRATIC START/ERRATIC CRANK).
2. Verify repair.