I've spent a lot of time over the past 2 month trouble shooting the dreaded P1170 code on a 2000 Protege with a 1.6L. Here are some tips I though I'd share.

Mine first started with a P??? for bank 1 sensor 1 too lean. I did a quick inspection for vacuum leaks, didn't find any, and decided it's been a long long time since the O2 sensor was replaced. So I replaced it. That's when the P1170 showed up. Here's what I checked:

Fuel pressure - Had to make a special hose assembly with a gauge since there is no pressure inspection port. Found pressure to be acceptable at 35lb with pressure regulator vacuum line connected and 45lb with vacuum line disconnected. This ruled out fuel supply issues. I turned the engine off and made sure the pressure held steady to ensure an injector was not leaking.

Engine Compression - Mine has 270,000miles and I was concerned about blowby. Mine seems OK with 140-150lb dry compression (3-4 "hits). As a tip, I have my crankcase vent tube removed from the rubber intake pipe. This helps keep the throttle body clean from the additional blowby seen with age. I have a clear fuel filter connected to the hose instead (<$3 at walmart).

MAF sensor - Back probed voltage on middle terminal of MAF sensor by sticking a straight pin into the rubber insulator at the connector. While at idle, voltage was around 1.4v. Snapping the throttle open quickly should quickly increase voltage (2.3V or so) and then go below 1.4 for a split second and then return to about 1.4v.

IAT (in MAF) - I believe this is the left two terminals looking into the connector on the MAF sensor. Mine registers about 1.7 k-ohm at ambient. Resistance should decrease as temperature increases.

TPS - Disconnect harness. Resistance between top and bottom terminal should be 4-6k-ohm. Mine actually measures 3.3k-ohm and functions fine. I hear these rarely go bad.

Coil Secondary Impedance - From secondary port on side to secondary port on bottom should be 7-12k-ohms.

Coil Wire - One measured about 2.5k-ohm and the other measured OPEN and I found my problem.

So the car never gave any of the normal signs of a bad plug wire so it must have been just open enough to begin causing problems. Needless to say it thoroughly confused the ECM into throwing the P1170 code. But the problems didn't end there. I erased the code on numerous occasions and even remove the INJ fuse under the hood but the code kept coming back. I even bought another MAF just to make sure. No better after 2 weeks of additional searching. So I back probed the O2 sensor signal wire (blue) and found that the voltage was constantly cycling between max (0.9v) and min (0.1v) within about a second no matter what engine RPM. Only after removing the positive battery cable from the battery was I able to erase all the corrupt data in the ECM. Code gone and all is well. Based on the research I've done there are still many issues that can create the P1170 code. Maybe these steps can help pinpoint yours. Happy trails.