04 Taco looses power

My 04 with a 2RZFE 4 cylinder has developed a problem. It was running normally, then lost power. I noticed that there was one very small sweet spot on the accelerator that would maintain the engine running at about 45mph. Fortunately I was only 3 or 4 miles from home. Any more gas, and it would loose all power. Any less, the same.
I am thinking about fuel delivery. Is there a filter somewhere? If I have a failing fuel pump, is three a way to measure pressure? I have a fuel pres. gauge, but it has a type connection that looks loke a tire pressure valve. I don't see a connection like that on my engine.
It could be electrical. Could be injectors.
Any ideas?
This truck set up for a year or two a while back, but I have driven it about 5K miles since then without problems.
Thanks!

 

You should get a bluetooth obd2 scanner and the free Torque app and link it to your phone. You can look at the throttle position, fuel trim, O2 sensor data, MAF etc. Its a good start to diagnosing something like that.

When checking fuel pressure, it may give a good reading, but needs an adequate flow rate also.

 

Could be but... IIRC you have an electronic throttle body, any codes? She could be in limp home mode. You can take it to O-Reillys or auto zone and they will scan if for free, write the current and pending codes down if any and get back to us.

 

Miles? and has anything been replaced last few years
is everything original oem

sitting messes with fuel pump and injectors
ever try injector/fuel treatment

good reason to run pure gas.....sitting with ethanol can cause fuel system rust

 

178K miles. It did sit up for a year or 2. I've driven it About 7-9K miles since it set up. This is an intermittent problem. I was able to drive it around a bit today without the problem.
I have these codes, although I don't think they are new
PO325 knock sensor
PO511 Idle air
PO135 Sensor heat circuit bank one.
When I go to LIVE DATA I can see Fuel sysA OL-Fault.
That one may be associated with this problem. I bought a pressure gauge at Harbor freight today. It was cheaper to buy that one, then to get a Schrader valve adaptor and T. I may have to somehow leave it hooked up so if (when) I see this problem again I can determine if it is fuel related. I thought about dirt in the line or tank. There is a filter. A black "can" bolted to the block, low on the left side. I don't want to change a fuel pump if I don't have too. Don't want to throw parts at it to see what sticks.
Thanks.

 

This is going to be a "fun" one... the live data message is telling you that the PCM has deteceted sufficient problems where it is running in open loop all of the time and it is not using feedback data from any of the sensors to adjust timing or fuel injection. The problem as I see it is going to be what is the criteria for setting the OL-Fault, if you can find that you have a starting point, are the 3 codes that are set sufficient to set the OL fault, dont know. You can fix the 3 codes and see if the OL-Fault goes away with them. The 3 codes present have nothing to do with fuel pressure.