Getting your car caught up on all the maintenance issues is definitely where you want to start. Although in your case I'd recommend doing your wiring harness first. You'll want to check the firewall wiring connector, where the engine harness plugs into for deterioration also,and for bare wires on the other side of that connector. If compromised replace it, (it's located on firewall, clipped to the body seam, just about at the end of the valve cover, maybe offset towards the passenger side. It's a grey rectangular multi wire connector). If the wires are also bare on the other side of that connector replace them. Volvo makes pigtail wiring repair splice sections of wire, that come with the correct connectors already installed with the proper insulating seal end that fits into that grey connector properly. If the wiring is compromised any further than an inch or two, I'd pull the passenger side firewall wiring grommet and do the splice repair on the other side of the firewall, inside the car. Just make sure that the volvo repair splice wire will be long enough. The repair wires are only available in white, so once you have the connector, and the wires, you can disconnect the connector, leave the wires in the bad connector, and just cut the wires at your splice point. That way you can see which colored wires go into which receptacle, then you can mark them, or just throw the old connector with the wires still in, into a plastic bag, and keep for future ID. Before you do the splice I'd recommend putting heat shrink on all the wires, I usually do a second layer of heat shrink, then do your butt connector splice. I recommend the connectors that volvo has, that are shrink sealing( you crimp it, then heat up the connector with a small hot air torch(soldering kit with a hot air tip), it starts to collapse, and a glue sealant flows out to the end of the connector, as it fully collapses. Don't over do it and over heat the wires. Then top it off with using the split plastic conduit on the engine side, that'll keep you good forever. You might want to consider pulling your intake manifold at the same time, and replacing your intake manifold gasket (it'll give you more room to wrestle with the wiring harness, and then it's easier to replace all your vacuum hoses there at the same time, you'll also want to replace all your injector seals, and possibly the injector housings if they're cracked. There's an O'ring on the injector, and also one on the housing. While you've got the intake off, might as well clean your throttle valve, it's probably pretty gross. I know this isn't the cool big HP stuff, but it's the stuff that will plague you. There's a lot more I could recommend, but this should keep you busy for awhile. Have fun. Good luck!
volvo power 
. I do have a bunch of seals that came with the car and do have the injectors seals, one injector seems to be sweating a bit. Ill do my research and get it done. Learning so much!
