UGHHH somethings wrong! Starter/Alternator/Battery related

sorry for the story, but this is how everything started... out of nowhere a few weeks ago, if u start the car when cold, itll crank right over and start, but when warm, if i turn it off, then turn it on, itll crank a little slower....

Soo last week i decided to put my battery in the trunk... we didnt have long enough wire soo we ran a temporary ground to the medal in the hatch in the spare tire well... im pretty sure its not a good ground... Soooo as i hooked the battery terminals back to the battery, out of nowhere the car started and the starter kept turnin... WTF?? soo i found out that mny solenoid was stuck closed soo i bought a new one.. problem solved... except.. everytime i start it, ill hear a loud CCCKKKKAAAA as soon as the car starts.. buit ever since a few days ago.. it would start fine in the morning, but when its running if i turn it off, ill crank reallll slow... then speed up and start the car. Yesteray, turning the car off, it wouldnt start back up... it cranked reeeeeall slow but wouldnt start..... soo i let the car sit for a few hours and tried again.. cranked real slow.. then speed up fast and turned the car over.... WTF? how can a battery mysteriously charge with nothing running???? Today i brought my battery to pep boys and it checked out bad... got a new one..... as soon as i put the new one in, it cranked slow, then started crankin fast and then it finally started.... right now i just got home and it wont start.. soo ukkl see what happens in the morning... what the heck is my prob tho????it seems like my battery isnt being charge, yet... by leaving it for an hour or 2, itll crank slow then crank fast and start... wtf???? some help pleasssse!

both power and grounds are 2 gauge wires.... over the summer, i had an incident which blew all my grounds from the motor and ish and had to be redone... ever since trhat, its been fine and the grounds are new

soo could be the alternator??? could an alternator be weak, but not totally crap out?? honestly, this would be my 4th alternator in 2 monhts from pep boys.. damnn but the last 3 totally crapped out..... when i keep the car ruinning, the stock gauge would read halfway... throttle response doesnt really bring it up or anythiong.. then when i turn it off with the key on, the gauge will read in the red

update:... just went outside after a half hour to try and start the car... 4 slow cranks within 8 seconds and then it turned over fast!!!.. car wont start tho.. ide have to hold the gas WOT... soo i turned the key off then on and it cranked real fast again with my foot WOT and it started..... when it started, the battery gauge read 1/4 of the way.. im gonna try replacing the alternator tomorrow for the heck of it and see... but any other advice?