Help with GMC envoy xl

[Dadlife524]

Hello I’m new to this site so i hope I’m doing this right. I’m having some issues with my mothers 2003 GMC Envoy XL. It cut off one day and wouldn’t start back up. It would crank but it wouldn’t turn all the way over. We thought the fuel pump went out on it so we put about a gallon of gas in it just to see if it was out. Nothing. My brother went through the fuse box and found the computer fuse had popped. I believe it did because the negative terminal is rigged up and it came loose. I’m not entirely sure. I say that because when my brother took his hand off the terminal it popped a second fuse. We zipped tied the terminal down and replaced the fuse and it cut right on but now we’re getting “random cylinder misfire” code. I think it had something to do with the gas we put in it because I’m not sure how long it was sitting. It runs and drives but sounds horrible. Any help with this would be appreciated. By the way I’m sorry for drawn out question. I’m mechanically inclined but diagnosing the problem is not my fortai.