First time to the forum and am looking for some troubleshooting help on my 2008 Impreza.
Start of problem: The problem started a few days ago when I took out the battery to replace my driver side turn signal. Upon putting the battery back in the problem began.
Problem: The problem has evolved throughout some troubleshooting. After putting the battery back into my car it would not start. It would fire up for about 1s then die almost instantly. After a few tries I found that if I started the car and gave it just a tap of gas, the car would start and would idle normally. When I finally got the car to start back up a whole bunch of lights lit up the dash (cruise control flickering, tire pressure flickering, check engine on, traction control on, etc.) and checking Torque the voltage on the battery was low (so many sensor problems pointed to battery) so I replaced it with an Interstate battery after getting it tested at an autoparts store. I fired it back up and now the car barely starts now but did fully start 5 times in a row (it fires up and nearly dies over the course of about 5s then proceeds to idle normally).
Troubleshooting: I tried unplugging the MAF before swapping the battery which very marginally improved starting capability. MAP sensor I also tested before swapping the battery and made the car start even worse.
Current state of the car: I had to drive the car home after replacing the battery and it drove just fine. The car died 3x over the course of about 2 miles but ONLY died when I was coasting in neutral up to stoplights. Engine braking and idling functioned just fine and the car seemed to drive normal. All lights are off in the car.
My next steps for troubleshooting would be to unplug the MAF / MAP and try driving to see if it still installs. I will likely drive it to a nearby auto shop to check the alternator. At this point I really have no idea as to what the issue could be. Google searches for hours really led to nothing.
Anyone have experience with symptoms like this? What approach should I take and what should I look at first?
Side note: About a week before when driving down the road my ABS, traction control and hill assist lights all came on. I did not get the chance to scan for codes as the lights when back off after a few miles. Not sure if this could be related.