i have a 93, 2.3 liter 4 cyl. and i have had an idle problem for a while and can't figure out what it is. it runs normal for a while but then runs about half the rpms as normal, and the rpms will jump around while I am driving and it is extremely underpowered when it is acting up. i have run many bottles of fuel injector cleaner through it but nothing seems to work. i also had all the spark plugs and wires changed, fuel filter and still messes up. the check engine light comes on but only while it is jumping around. sometimes it corrects itself but most of the time it doesn't. any suggestions?