check all of your vacuum hoses especially the ones that go to the fuel pressure regulator,make sure they are not cracked or dry rotted.if all that checks out try checking the timing, the timing belt may have jumped time or the distributor could be going bad.if you haven't replaced the fuel filter now would be a good time to do it.it could also be a bad coil, try spraying the coil with a spray bottle, with the car running, at night time(so that you can see if the spark from the coil is arcing out somewhere).most importantly look for bad grounds,check your battery cables,and make sure you have the correct sparkplug wires with the steel boot covers preferably bosch.just a few things you can do real cheap or for nothing to try and lead you in the right direction.