sometimes while driving my 87 cavy(2.0l, ohv), i punch the gas and it boggs down and im pretty sure it backfires through the intake. what would cause this?

Could be several things like u need to replace the spark plugs,and wires, or distributor (check for cracks in plastic).U may have a worn vacumm line or the tbi ur injector maybe dumping fuel or have a uneven spray pattern and needs to be replaced.I would replace ALL the tune stuff plugs,wires,distrib cap and if after checking the injector the spray pattern is drippng or erractic replace that.It also could be some emission problems like a worn out or particially clogged catalytic convertor and even a clogged/or particially cloggd muffler.I would do a cat but,doing the muffler at the same time is a good idea being if the cat is history the trash blows into the muffler and blocks it up,so if u do the cat and have this happen again the muffler is the culprit.Do both to eliminate this waste of money if u replace the cat as to not create teh problem again shortly there after,I speak from exper on that one.Hope this helps if I am incorrect or left something off may others add or correct my responce..

i did the plugs and wires and it did it b4 and after. the car doesnt have a distributor it has 2 coils. ill check the injector.it just passed emissions so i would think the cat is fine but this i my daily drive so i want to fix the problem.

thanks for your help

U may want to pull ur egr valve off and check for carbon build up.If the egr's pintal which moves up and down should move freely and not stick,also the carbon built up around inside of that area and the age of the part could mean it's sticking or the rubber diaphram inside is loosing vacumm which inturn can cause the cars idle to be affected and inturn affect the emissions and make it run rich or lean.IF ur version has a vacumm line which it should I think just disconn it and see if the problem persist,if no vac line I would start replacing the vac lines being its 20yrs old and should only cost u about 10 bux or less to do so.Also a old O2 sensor I would repl being u bought it used and do not know if its really old,Were ur emissions high just getting by or below ur states allowable specs.U would be surprised how a new catalytic convertor can resolve issues even if it passed,mine passed but was high on the CO as I recall,repl and dropped it to nothing the next yr.Just some things that came to mind while sitting here tired and running thru the possibles.