Hey guys, new to this but thought I'd give this a try. So I have a 97 ford ranger 2.3 I'm having issues with. Was running rough for a week changed bugs and wires still had two codes pop up cylinder 3 misfire and system to lean bank one, I changed the pcm tips iac pcv valve air filter an both o2 sensors were already done and did the timing belt and was triple checked and I'm still having issues getting it started, any thoughts?

 

Stop replacing things.
An engine is still an engine, computers and sensors can't change that, they make engines more reliable but don't change what makes an engine run.

First stop would be a compression test, remove 1 spark plug from each cylinder(dual plugs), check it's tip to see if it tells you anything about that cylinders condition.
A compression test is invalid unless all cylinders are compression free, so one spark plug MUST be removed from each cylinder to test 1 cylinder.
Unplug coil wires on both coils, you want a no start
Put compression gauge in #1 and crank engine, you need to hear compression stroke at least 4 times.
Write down results
Move to #2
ect.......for all 4 cylinders

You can rent a compression gauge.

'97 2.3l has compression ratio of 9.4:1 so you should expect above 170psi in each cylinder.

If #3 is lower than the other it is most likely a valve issue which is common on Lima 4 cylinders.

The #3 misfire is most likely the source of the Lean O2 code.
O2 sensors read OXYGEN levels in exhaust NOT fuel levels
If a cylinder is firing correctly it burns up most of the oxygen but not all of it.
If a cylinder is running rich O2 will see too little oxygen.
If a cylinder doesn't fire then all the oxygen goes out the exhaust and O2 sees it, so reports Lean.

Most common cause of rough running at idle and in general is a dirty MAF(Mass Air Flow) sensor and/or a vacuum leak.
First test for vacuum leak, warm up engine, it should idle at about 750rpms.
Unplug the wires on the IAC(idle air control) valve.
Idle should drop to 500rpms or engine may even stall, either means no vacuum leak.
If idle stays high then start looking for the vacuum leak, if #3 is missing then it could be #3 intake gasket is leaking.
Clean MAF sensor every 2 or 3 years.

Run a can of Seafoam in the gas take once a year, it helps keep injector tips clean.

You can also rent fuel pressure gauge, computer can't monitor fuel pressure, on a '97 it should be 35-40psi

 

Thanks I'll try the compression test I did run a fuel pressure test with koeo got up to 10 psi and when I tried to start the motor got up to 30 psi could not get it to start that day couple days after got it to start and then when I put the parts it no start again.

 

The 10psi means pressure is leaking out over time.

Pressure in fuel system should hold no lower than 25psi for a week or two if not longer.
There are two valves that hold pressure in '97 fuel system
Fuel Pressure Regulator(FPR) located on the fuel rail, it has a vacuum line attached.
Check that vacuum line for fuel or fuel smell, if found replace FPR.

Second valve is on the fuel pump in the tank, it is a check valve or backflow preventer valve.
The in tank fuel line can also crack, so fuel and pressure is lost but there is no external leak or smell of fuel.
30psi running is OK but low, 35-42psi is specified.

You will probably get a faster startup by cycling the key on and off 3 times, this will build up pressure in the system, then try to start.