???HELP-93 Sundance stuttering problem???

I have a 93 Sundance(4cyl,manual). It has been stuttering lately when I give it between 25%-50% throttle. It seems to stutter worse when it is rainy or humid out. If I give full throttle it accelerates normal. But if I give it anywhere between that 25%-50% range it stutters bad, where the hole car jerks violently at slow speeds and noticably at higher speeds. It seems to do it at a certain RPM range also. I don't have a tach but I would guess it is between the 1500-3000rpm. If I keep the RPM's really low or high(just like throttle under 25% or over 50%) it doesnt seem to do it. I have a check engine light coming on also which I am going to have checked by a friend. Thanks Will