Car sluggish and service engine soon light on+++FOUND the problem

I was out driving and the car became really sluggish, not a lot of power...became really sluggish then service engine light came on.  Stopped at a red light and pressed down on accelerator, car took off very slow and took a minute or two to get up speed.  It continued to be sluggish.  It doesn't "sound" normal either.  Any ideas why it's sluggish? It kind of sounds like a muffler or something (just guessing).  Can it be bad gas?  It sat for about 2 months before I was able to get it fixed.  It's at about 1/4 tank now.

Thanks everyone...it was a bad plug wire...it was fried...I still think maybe I need to get the exhaust checked...I smell fumes when I start it and as it sits and idles.

First thing is to find the code for the check engine light that came on....... but from the sounds of things, I am guessing at an EGR valve..

my 84 was doing about the same......would not idle .... kept dying .....running rough...took it to my vette mech    put on computer ...had a bad vaccumhose leak .... could not find the  leak without computer...replaced hose runs great

Is it possible the the Catalytic Converter has gone south?  If it breaks and or turns all the exhaust is backed up and no power, could be "sluggish"

You said the Check Engine Light came on. When the CEL illuminates while engine is running, it indicates it set a code. Unless this is a 96, a plug wire generally can not set a code. I'm curious, what was the code?

I agree with a previous post that you catalytic converter might be plugged....

My 90 recently started doing the same exact thing, started running sluggish, service light would come on after about 10 or 15 minutes of driving. shut it down light goes off and doesn't come back on for another 10 or 15 minutes. Mine was the EGR Valve, changed it out and it was running like a scalded dog and no more light..

If you think it's the cat, go rent a "Back pressure Tester". You remove an O2 sensor and screw this thing into the O2 bung then rev the engine power brake it or whatever you gotta do to stress the engine a bit.  should not see more than 2 or 3 PSI