Engine is sputtering

The check engine finally came on and I struggled to make it to work luckily I was two stop lights away. The light blinked three times but now stays on. I went on in the afternoon and started fine actually engine sounded better then before. Drove around the parking lot with no problem then parked it. The check engine light stayed on. I really havent noticed the gas mileage dropping as I do pay attention. It slowly has gottne worse but when I add Lucas Fuel cleaner it seems to give no problem for about half a tank a gas. The other weird part is when Im driving it starts to slip and that got real bad yesterday. I think transmission but yet why would it struggle when its in park. Could be two different problems I guess

When I hit between 35-50 mph my Vue shudders. It goes into gear fine and seems to shift normally. At the 35-50 mph speed range it sometimes vibrates intensely from the shudder. Is the bad torque converter likely the cause for this problem? If not, is there something else you would know of that causes this?

Thanks

There are no check engine lights that come on. The color of the transmission fluid is brown and it does not smell. I don't know if the fluid has ever been flushed. The carfax gave no indication if it was done or not. Would a bad torque converter be the most likely issue?

Another thing I noticed is when I am traveling steady at about 35 mph, the rpms are in constant flux between 1400 and 1500. Is this a related symptom to any the bad clutch or solenoid? What is the best way to get a code if there are no lights showing?

2004 saturn vue awd I was told I had a torque converter shutter. At 30 to 50 mph gm 4000.00 to fix. How can I fix this? The 8th digit in vin is a 4 what type of trans do I have. I was going to add shutter stop but unk what type of trans I have. I have seen reports of no dip stick sealed system some say there is in line with the elec fan motor black in color? Thank you.

Do I have to go to a GM dealer to get a professional scan done? The fluid is brown and smells like normal transmission fluid.

My Saturn has been a nightmare come true. The latest problem that I am facing is this. On my way home yesterday, driving 35 mph, my Vue started running rough and the engine light was flashing. It started trying to stall out while I was driving. It got to the point to where it wasn't even going 15 mph with the pedal all the way to the floor. I thankfully made it to the corner by my house and coasted it into my driveway where it died. I tried to start it a couple times but it did not start. I went out today and started it but it only took about 20 seconds before it started to stall out again. So here is a little history on this disaster of a vehicle, ECM was replaced 1 year ago; timing belt, serpentine belt, water pump all replaced 9 months ago; both front cv shafts replaced along with brakes, all of this since 11/2013. Obviously a bad investment on my part lol. Anyway, back to the issue at hand. Please let me know what you think, ask questions, I will answer them ASAP, thanks a million!

I am going to try to limp it to the auto parts store tomorrow to get some codes. I really hope it is a cat! I will let you know tomorrow.

I am sorry about the delay, I could not limp it to the parts store and ended up having to have it hauled to a shop. The codes that they pulled were P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0318, P0442, P0128. The shop said that it is almost all to do with sparkplugs and coil packs. What are your thoughts. I have them waiting before they tear into it.