Blinking service engine soon light / shuddering
 

So I was in georgia for 2 months with work and when i came home and drove my car i noticed that the car was a little hesistant when accelerating. After driving it for a little while and thinking maybe it was bad gas i put more gas in it and it didnt clear up. It idles rough and seems to be missing and lacks power going up inclines. I also have noticed that that the service engine soon light was blinking in the car. I did a tune up on the car i replaced the plugs, wires, pcv, o2 sensor and air filter still the car continues to run horribly. I noticed that the exhaust has almost a put-put sound to it almost like something is stuck inside the exhaust. I was just wondering if anyone else had this problem before with the blinking service light and performance problems. Could it be i have a bad or clogged cat or resinator or could it be something else i have already previously replaced the intake manifold gasket also. I have a 2001 sc1 it has about 138k on it and ilove it and do not want to get rid of it. Any advice would help before i go spending the $300+ to get the cat and resinator replaced.

sounds exactly like what happened to my 97 sc2 as it dropped a cylinder -- but let's hope your situation is not so dire

The blinking SES light is for an active misfire i do believe. Get codes read at autozone or similar -- the misfire code will point you to the cylinder at issue. I'd normally say "check plugs and wires" first" since that's the most common cause for a misfire -- but you've already done those.
The putt putt you hear in the exhaust is because there are only three putts instead of 4.

Post codes and we'll take it from there

So I was messing today and decided to see if I had spark in all the cylinders to my suprise I had no spark in one cylinder (the cylinder that's second in from the left not sure of the number off the top of my head). So after I had already changed the plugs and wires and over the past summer I had changed both coils the only thing I can think of is possibly the ignition control module. If anyone can possibly give me some insight id appreciate it otherwise I might go for broke and change it. And to the person who replied and pointed me in the direction of the cylinders you may have kept my saturn on the road I appreciate it.

New coils have been known to go bad ... recheck your original work/wiring and tightness

get the codes read (might be more than a misfire code and therefore enlightening)
swap the coils and see if the miss follows the coils

Replaced the module today with a new one reconnected battery and still no spark at coil one...... I really didn't think it was a coil being that I just replaced them both not to long ago. It was pouring rain today so I didnt get to swap the could but I'm going to tomorrow if it is the coil I should have a warranty on them and get a replacement for free. If it's not I'm absolutely lost on this one I have no idea what could be causing this if the plugs wires coils and icm are new what else is there to replace? I read somewhere that a alternator that is going bad could effect this also I don't know how true that is but at this point in looking for any solution. If the coil swap doesn't work Im gonna take it to auto zone to get the codes read I know this is the first thing I should have done but I live no where near one. So if it isn't the coil can anyone else point me in another direction? Any help greatly appreciated......

Crankshaft positioning sensor????? Gonna try that if it's not the coil gonna swap them tomorrow if no cps change Thursday after work. Will post updates.