diagnose misfire problems,p0300and p0179(rndm mis,o2sen)and sudden loss of power

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especially if i start it in the am, itll misfire anywhere above 1500 rpm sounds kind of like its slurping air and very sloppy, i checked vacuum for leaks and its sealed properly, and i have been forced to drive the vehicle for a while to work (80 mile round trip 5 times a week ) and today i noticed that all of the sudden my vehicle lost a lot of pulling power while i was giving it some gas on the highway, and now no matter what i do it seems that if i give it gas anywhere above 2500 rpm it wont pull any harder, wondering it its got something to do with the trans ? also, can you help me diagnose the root of the problem in the first place ? ( as far as i got was i need spark plugs, wires, distributor cap, (( unfortunately my vehicle has the ""spider"" injection system thats famous for breaking on my engine,... just very confused and scared as to why the sudden loss of power, ( and misfire reduced btw (usually happens when im close to shifting gears now barely any misfire, and half my horsepower....) Help !!!!! i really need to have a proffesional opinion of whether i should sink more money into it or buy something new !! if there is any way of speaking live to a consultant on this matter i would greatly appreciate it!!! "" thanks in advance !!""