Diagnostic Codes 12 and 22

[87GTPopTop]

Hi all! 1st time poster but long time Celica owner.
I recently started having problems with my 87 celica and when I ran a Dignostic, I got codes 12 and 22. Code 22 is pretty straightforward and I'll change the water temp sensor this weekend.

I am not sure where to start with code 12 (Engine RPM Signal). Plugs? Wires? Injectors?

Here are the symptoms I have: When driving along at any given speed, the engine bogs down and the check engine light appears. It doesn't feel like it is in danger of stalling but I have to give it gas to get it back to normal. Then, the check engine light goes away and the car runs just fine. Note that this happens only after driving the car in the morning or after it has been parked all day at work. I think this is mostly related to the water temp sensor but I can't say I know for sure.
Thanks!

1987 Celica Gt
3S-FE
Everything is stock except for the Green air filter in the stock airbox
213,000 miles
Tuned up @ 195,000 miles
New O2 sensor 1 month ago

[alfredo300zx]

HI, my celica 1989 is having the same problem, did you find any help?

[RobMilkshakes]

He hasn't posted in over 5 years, you're best bet is to start a new thread and thoroughly describe your exact problem.