89 LX miss when accelerating

I was going down a merge ramp the other day in my 1989 LX 5 speed. I kinda got in it & noticed my car lost power & the motor missed enough I could feel a shake in it. So I got out of it & cruised easy up to speed. When I tried to accel again it did this again. I ended up just taking it home. So tonight I wanted to try it again. It started fine & ran fine through town. I went out in the country & it ran fine even accelerating. So then I kinda got in it some & it started missing. I was in 4th gear at 3000 rpm & it just sputtered & would not gain speed or rpm. Shifted into 3rd gear & 4000rpm... same thing. Turned around & went home. 5th gear & 2000 rpm same thing. If I baby it while gaining speed it seems OK though. Maybe just a little down power though too. Any ideas?
Thanks guys,

when was the last time you cleaned your carb?change fuel filters?

Never cleaned the carb. Changed both fuel filters last June. Changed cap, rotor, plugs, ait filter then too.

Have a look at your leads if you havent changed them. They are a big source of problems like that.
If you ment June '04, then have another look at your Air filter, if youve got a shitload of dust in there it will limit your power and cause missing.

leads?

The updates were donw in June of 05

The leads that connect the spark plugs to the distributor. They are usually about 1cm thick and run from the back of your spark plugs into you distributor.
My 3g was missing before and it was all because of the leads. I picked up a set of Bosch leads for $25(AUD) from my local car shop. You will easily be able to install the leads yourself, you just pull them off, then plug the new ones on. NOTE be sure that each piston goes to the right plug on the distributor. The plugs are numbered 1-4 reading like an asain (right to left) and the distributor takes plug 3, plug 1, plug 2, plug 4 from the bottom up.