Major fuel economy loss

[Jolting]

I drive a 97 DX 4dr 5 speed 151k miles

I went from 30-35 mpg avg 300-320 a tank to 16-22mpg 190 to a tank.

Today while driving I noticed a sudden loss of power for just a moment as if I let off the gas petal, this happened around 3 times in 20 minutes. The fuel filter had not been changed in ages so I changed this once I got home, I haven't been back out on a road today since then, but I felt it may be relevant.

I replaced the cap and rotor because as I was going down the interstate the rotor malfunctioned and got all burnt up, when this happened I started having misfires, I did not drive the car more then a 1/4 a mile when it happened. When I got home I replaced the plugs/wires with NGK iridium. I want to say that the fuel econ dropped shortly after that happened.

I have also replaced the first o2 sensor.
(Just before the trip where the rotor went out)

CEL Code
0441 Incorrect purge flow. (I have had this code for probably a year now, I replaced the control valve but it wouldn't work) --- Highly doubt thats to blame, but would like advice on what could cause it.

 

[RonJ]

So at this point, you have replaced the plugs, wires, cap, and rotor, right? Have you checked the ignition timing with a timing gun?

Have you recently checked for codes to see whether any new ones have popped up?

 

[Jolting]

I had to do some stuff so I had to unplug the battery so I can't check for any codes right now, however I have a little Bluetooth obd2 that shows me codes and I haven't seen anything new. I have not checked the timing as of yet. I'm limited on tools but I have a local shop that I help find parts for and they let me use their stuff. So I will try and get that on Friday, if I can't tomorrow.

Replaced
Plugs
Wires
Cap
Rotor
Fuel Filter

 

[RonJ]

Have you checked the ignition timing?

It's quite possible that when the rotor failed, the coil was damaged. Resistance test it:

 

[Jolting]

I'll pull out my voltage meter out tomorrow during my break and test the coil. Thank you for the help, I'll let you know what I find out when I test that. The timing light has to wait though.

 

[RonJ]

Make sure the coil is room temperature when you do the measurements. When you set the meter to measure resistance, touch the two probes together and read the internal resistance of the meter. This background resistance reading must be subtracted from the primary winding resistance reading to obtain the true Ohm value.

 

[emerican]

Let us know reults on the coil

 

[Jolting]

I haven't had time to pull it apart and check it yet. Long class periods and long shifts. Plus something went wrong with my brakes now. When ever they start to heat up if I go to slow down there is a loud banging noise that I can hear and feel.

Also for some reason it seems my fuel economy went back to normal. My OBD device now reads it at 30mpg. I'm going to keep watching it to see if it goes back down again. I'll let you guys know as soon as I can get out there and look at it. Wed, is the next day I can think of that I will be free. I still plan on checking the coil.