Runnin Rough

Hey all. Got a problem . It kinda started about 2 months ago. I know, i shouldv
done something about then but i only put a few miles on the car a day because
of the 161,000 miles on it, and the engine is coming out hopefully this summer anyway. But anyway, problem is when i start the car up it idles like crap. Feels like its gonna stall. Check engine light comes on. Try and drive it...no power what so ever (like it has any anyway!) heh. Then after a mile or so. It goes back to normal, and check engine light shuts off. Sometimes even when im driving down the road the rpm's will kinda jump down real quick to 400 or 500, then go back up to 900. A buddy at work said it sounds like the TPS sensor , but id figure id ask you guys first since i seem to get more reliable answers here instead. Thanks for any help!

91 2.3 Lx Hatchback - project stanger banger
Parts so far (sitting in my apartment all over, closets, living room..
8.8 rear with 3.73 gears
Mac 2 1/2 crome tailpipes
5.0 Calipers
5.0 rotors
5.0 KYB shocks and struts
Design concepts Turbo wing
GT ground effects
(on the car)
Aftermarket crome 5 stars
225/50/15 front 265/50/15 back
Mach 1 hood
Billet shorty antenna
Crome door handles

Yea, i was thinkin the same thing, a had bought most of the stuff for a tune up a few days ago. Wires, plugs, high milage oil , oil filter, air filter, and engine restorer. And i just talked to another friend of mine where i'm gonna do the tune up and he said the same thing you said, so im gonna go ahead and do that first.
And hopes that cures the problem. Thanks for your help.