Hard to start, begins sputtering when transmission is shifted into gear

The truck I've been working on with my best friend, for lack of a better way to put it, is a nightmare.
We put in the third transmission on Thanksgiving weekend, it just blew the head gaskets on it's second motor, which we discovered when changing the spark plugs and radiator last night through this afternoon. We have another starter to put in, but we had to catch some sleep.
It has the infamous "death wobble, " doesn't like to start (which we're hoping the starter will fix), and though it idles fine once it starts, it starts sputtering once you stick it in gear, and it has very limited acceleration on the road. You can stick the throttle to the floor and go from 0-40 in about as many seconds, it's ridiculous. We know it still has power, it's the only thing we've got to tow the tree debris trailer for work, and it runs the same with a load as without, that is to say, barely.
Another issue is that if you give it some gas, it makes a noise somewhere between a cat and a goat when you let off. We think it's something with the transmission, but not quite sure.
This truck has given us hell, but we refuse to give up. We need some help to make sure Ol' Betsy stays on the road, if anyone could point us in the right direction, that'd be fantastic.
We're planning on putting a third motor in soon, haven't decided if we're going to rebuild one to put in or get a temporary motor to put in while we rebuild the old one. A new starter will be going in at some point over the next couple of days, so I'll let y'all know how that goes. We were planning on redoing the suspension, but then we blew a head gasket, so we're putting that on hold for the moment.
I appreciate all of your input in advance, and now that I've put this on the Internet (the best way to get as many ideas to sort through as possible), I'm going to sit my butt in my recliner and catch some rest. I look forward to reading what y'all think about this.