2000 Chevrolet Cavalier • 2.4L 4 cylinder 2WD Automatic • 130,000 miles

Within the past few months my vehicle has started having problems starting. It takes several seconds to turn over, and sometimes once it has turned over, it idles rough while still parked. This usually isn't a problem when I start it for the first time of the day, but if I drive somewhere, park it to do something, then come back to it to start again it struggles more. If I notice it is struggling to start, I sometimes just turn it back off and try again and it usually has enough to turn over normally. It seems to be getting worse and I am afraid that at some point it will not start for me.

In addition, my vehicle has had a serious decline in its fuel economy. I used to get close to 400 miles to the tank (~13 gallons) and now sometimes I don't even get to 300. I was thinking it might be because I started driving more city miles, but even recently I went on a road trip, all highway and the most I got to the tank was 310 miles.

Within the last few months I have
-replaced the fuel pump
-new spark plugs
-new battery
-new tires
-regular oil changes
-new fuel filter
-tried several fuel injector cleaners including BG44K

Please help I have spent so much at the shop with wrong diagnoses. Thank you very much.
January 29, 2014.

Either corrosion of battery terminals or corrosion on starter connections or engine ground.

Jan 29, 2014.
When we turn the key it powers on, but it struggles to turn over like it may be a fuel issue. We have to hold the key cranked for several seconds before it gets enough gas (for lack of a better understanding) for it to turnover. It only happens when the car is already warm, not usually on the first start of the day. If I press the gas pedal it also helps it start up. Thank you for your help.

Jan 29, 2014.
Perform compression test.

Jan 30, 2014.