check for vacuum leaks, spark, ICV, etc. See the newly available Bentley PDF for a great troubleshooting section.
Does it act up when only cold, only warm, all the time?
If you go on the throttle a little, does it stay smooth and steady without much messing around?
Are you low on gas?
Plugs are cheap, if you've never replaced them it won't hurt. Get coppers, no platinum.
More than likely a vacuum leak, hose clamp has slipped off or theres a crack somewhere. Injectors tend to get stuck open, which will give you a flooding condition and it will be tough to start.
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