Bike loses power while accelerating

[HowDoICarbs]

Hi everyone. I recently bought a 92' Seca (off craigslist, where all good things come from) for pretty cheap. It had an oil leak from an old clutch cover gasket, so it was in the shop after I bought it for awhile. (paid $120 for that fix). I just recently got it back I haven't gotten it tuned yet, I seriously think it could use one. Anyways a few days ago I tried to get onto the freeway and as I was getting into the high rpms (9k-10k) I was lurching a lot. Bare in mind ive only rode dirtbikes (single cylinder) before this, this being my first bike. Like I said it lurched a lot at first but then smoothed out and it was fine. Fast forward to the next day, I'm on my way to work going through an intersection in traffic and all of the sudden while I'm accelerating from a stop my bike loses power and wont respond to the throttle at all not even a sound, until my Rpms drop down to about 4k. Ive ridden around a lot since then and the problem seems to be more throttle related then Rpm (I just use RPMs as a guide since my speedo doesn't work). Any time I open the throttle wide in ANY gear she will lose power and if I keep trying to give it some, it will eventually come to a stop and die. If I let off the throttle it will drop down to around 4k before coming back unless I shift up or down a gear then it will come back. It becomes more prominent at freeway speeds as I have to open the throttle more to get up to speed and I can say that having your bike die on you in the middle of Arizona traffic is not the best feeling ever. As of right now I cant even get up to 60Mph (I think) that or everyone on the freeway is driving like a bat outta hell. My tank is a little rusted, the bike isn't leaking (except the fork seals). Any suggestions would be great. I really don't want to take it to a mechanic. I would like to learn how to work on the bike myself,although that might be some time considering I just now located my idle adjustment screw, and as of writing I still have no clue where my air filter is located, but heres to hoping right?