check your spark... pull one plug then connect a jumper wire or cable from the threaded portion of the plug to a good ground...crank the engine over..does the spark look blue and consistent? you can get a cheap spark tester at any auto parts store for less than $5...should get a spark length of 28k volts and it should be consistent...the igniter module would be the first part i would replace if spark is weak...other possibilities: a bad connection at the crankshaft position sensor or a bad CKP or CID sensor...not sure but i think the CKP and CID sensors are both inside the distributor (distributor would need to be replaced)...a clogged catalytic converter would cause hard starts also | 
