Flashing check engine light. Shaking while driving. Sputtering at idle.

2002 Toyota Tacoma --- same issue this morning as I was going to work. 159900+ miles. Check engine light has been on. Put a code reader on it, came back with P170. Cannot locate the problem.
Cold morning around 36 degrees F. Felt like it was hesitating or a "slip" when easing away from stop signs, at red light it shuddered some. On interstate at around 68-70 miles an hour, rpm around 3500?, it started shuddering like it was going over reflectors or variations in road pattern. I let off the gas and it stopped shuddering but check engine light started flashing about 1/4 mile later.
Any clues would be helpful.
I had the sparkplugs and wires replaced a couple of years ago. I had the truck in for service within the past 3 months and they hooked it up telling me "everything looks fine", but then again I asked them to see their computer code would be and they didn't offer that nor did they reset it like they said they would (among other things I had to remind them of before I left). Soooo, not feeling warm and fuzzy about Toyota dealer's efforts to address my problem. Back to the Under the Oak Tree garage.

 

My issue was a cylinder misfiring, i found which cylinder it was, replaced that, and put all new spark plugs in, and it works fine now, hasnt happened since

 

yo that's it, use DENSO or NGK spark plugs, using Bosch or any other brands will cause misfires fo sho

 

Go to autozone and have the code read (for free). That will tell you more about the issue.

 

Was told by shop that it was one of the coils, so I had it replaced. If I had more time I would have done it myself. Duty called and you can only bum so many rides from friends.
Upon picking it up, I put it through the paces - acceleration smooth and it is back to being peppy. Idle seemed high and was a little "rough" like a misfire almost. I called the shop, then they said I needed induction and injection cleaning (of course). Truck has 160,000 miles so it probably couldn't hurt if I had a spare $200+ dollars.
I used to put in a small bottle of Lucas every 3rd or 4th fillup. I have been negligent in the treatment.
I read up on the induction (throttle body) cleaning which doesn't seem difficult except for removing stuff to get to it.
Any advice or suggestions?

 

I had a similar issue in my old '91 pickup and it turned out to be a faulty distributor cap that was holding moisture

 

A flashing CEL light means that the ECM has detected a condition that most likely will result in catalytic converter damage. It could be a misfiring plug, bad injector, bad fuel pressure regulator, etc. Not just a misfiring cylinder. (Though that is the TYPICAL cause) Since spark plugs have been recently replaced, check plug wires, plugs, and coil connectors. If you don't see something obvious have the ECM checked for the code. You shouldn't drive a vehicle with a flashing CEL light though.

 

1/31/17:
Yep, now mine 2011 Taco is doing it to: it "sputters" at speed from 25ish--40ish and smooth out at higher speed; during the sputtering, if I give it gas, it seems to either stops the sputtering or "covers" it. I have not done a tune-up/spark replacement for a while, so I hope it resolves it. Thanks for all the info. from everyone above.

 

This all sounds very familiar to the post I made this morning. Runs great at times, runs like crap at times, this afternoon I finally got a flashing check engine light went it was running like crap. Shut the engine off, waited five minutes, started it up and all was back to normaL. Pulled codes and the only ones I found were evaporative codes. I don't think any evaporative problems would cause such a poor running condition. I'm starting to wonder about the injectors like one of the earlier post in this thread talked about.

 

How did or do you know this info my friend?

 

Who did the work?? +1

 

Same plugs and what-not replaced?

 

Similar problem as mentioned above. Ran the code and replaced the coil pack. Truck threw another code this morning so I'm leaning towards replacing all spark plugs and wiring. Any other suggestions? Fuel injection cleaning?

 

I ended up replacing the fuel injector and didn't have a problem after.

 

Had this same problem, took it to a code reader and it said it was cylinder 6 misfire. Replaced the coil for that cylinder and it runs great now.