tomlock_pa

My old Jeep was sitting out in the Humid, rainy PA winter for a few weeks, unused and unstarted. One day went out to use it and it didn't start, but didn't have time to check into it - just hopped in another vehicle and left it there. A few days later, tried to start it and it fired right up! Idled for 45-seconds and shut it down, no worries (I thought). A week or so later (so it hadn't actually moved in 3 weeks), tried to use the vehicle, but it wouldn't start - not even turn over, just a little click and [nothing]. Tried to Jump-start it, which finally worked...took a long time. And even when I got it started, it wouldn't stay running unless I kept my foot on the gas. Put it in the garage to dry out a bit, put it on the trickle charger for 28-hours, then tried it again...{nothing} --- just a click and not even an effort to turn over. Looked online for some hints and found out about cleaning the terminals and grounds, so I did that today. Well, I cleaned the terminals and a couple of the grounds which I could reach and actually turn. I could only reach one of the two grounds down on the side of the engine block - it would not turn. Both of these ones are filthy - covered in oily grime. But I don't know how to get to them and get them apart/clean. So I left them dirty.
the old Clunker fired right up for me with a turn of the key, and it idled just fine!
However, when I tried to back out of the garage, it sputtered a bit. And when I put it in Drive to go for a test ride, it sputtered more, the RPMs went down and it almost stalled - I had to gas it to keep it running, but even that didn't do much. Every time I put it in Neutral or Park, it was fine. Soon as it is put in gear, it sputters and hesitates. Took it on a highway to 'clean it out' and it over-revved in the lower gears and then would not go into OD once I reached a normal cruising speed. Also about this time I noticed the gauges were not working. Not sure about anything else, because it was just me in the vehicle (IE couldn't tell if brake/signal lights were working).
So in summary, cleaning the terminals and a couple grounds has it starting/idling fine, but now it won't run right when it's in gear, and it's not shifting right.
Thanks in advance for your ideas.