wont idle correctly

my 88 s10 w/2.5 stopped idling correctly Ive put new plugs,wires,rotor cap,rotor,fuel filter,pcv valve,breather filter,filter,o2 sensor.I turned up the idle so it will run,my computer wont give my anything and I replaced It and still nothing.ses light comes on when you turn on the key.The quick tune said the comp was dead.Ive reset it with the battery and nothing.When you first start the truck it smell like rich exhuast,the truck runs ok but its using lots more gas and if you stomp on the gas without the engine reved up it bogs down then backfires first then revs up.I dont know if it jumped time or not I havent checked that yet.This truck is old I bought it brand new in 1988 original motor in it,it doesnt smoke or use oil and runs good.Any suggestions of what else I could check?

Check for vacuum leaks and EGR valve for sticking open.
MT

Check the timing!!! Also, make sure the wires go to the right plugs (I made that mistake once at 2:00 AM). Make sure there isn't a wire or vacuum tube that must be disconnected while timing, any manual should tell you. What brand of plugs, wires, cap, and rotor did you buy? A friend of mine had an '89 blazer and he tried some bosh stuff, the truck ran like junk and it took him 2 months to figure out the truck didn't like them.

Hey getting back to you guys late ive been working alot here lately.ive checked the timing and its ok and it advances with the throttle,I only use ac parts if I can I think the plug wire were just standard I know they werent bosch.I still have to check the egr valve ,hopefully I can work on this next week,Ill get back and let you know what I find,thx for the help.