Leave it coiled up like JJD stated. It may be acting as a choke when you have it rolled up and this isn't necessarily a bad thing. As long as the radio is seeing a good match I would leave it be the way it is coiled up.
And yes JJD, they aren't swing monsters for sure but like you said add a nice 1x2 or even a 1x4 and watch out!! They are clean, clear sounding radios and clean in equals clean out. I've not noticed any channel rejection issues with the 980, but I haven't been close enough to anyone to see if it's an issue with that radio. I know my magnum 257HP and my optima MK3 do have this issue. Way over sensitive receivers. Nice thing about the Icom 746 I have is being able to use NR and the twin PBT as well as the notch filter. Man does it get rid of unwanted crap quick!! But it's an SSB radio and I know that. My cobra 29lx le is a nice radio as far as AM only and with the 1969 final mod does rather well. Someone in TN did the work and I picked it up from a trucker in Michigan while I was working there. Also got a nice predator 10k antenna as well. Use it with a 4 magnet mount on top of an old Nissan Pathfinder with my TNT 600hd from time to time. Gets the job done when I need it to. Anyhow. Enough BS.
Matt I truly hope that you get all your things right and have fun. That is what the hobby is all about man!!