Battery - needs to output what the CCA rating is or better.

Grounds - main needs to measure at 0 ohm from the negative post to the end of the cable down by the starter; no more than 0.1 between negative post and alternator case.

ECT - check it's output with the engine cold to see how close it is to the ambient temp.

Intake Air Temp - same as the ECT, check that it is close to ambient with engine cold.

Fuel - pressure with key on, engine off should be 49-58 psi.

Fuel injector - Measure the resistance between fuel injector terminals 1 & 2; 5-20 ohms depending on the injector temperature.

Check power to the injector - should be battery voltage with key on, engine off between terminal 2 of the connector and engine ground.

With engine running, you should have a ground signal on terminal 1 of the injector.

Check the coil is firing.

Is there any noises occuring when you first start the engine?

Is it full of clean oil?

What brand spark plugs did you use?

How many miles in the car?

What brand O2 sensors?

 

Fuel injector pin ID

 

Will begin working through some of your suggestions.
125k on the odometer
Denso O2 sensors
NGK iridium plugs
battery is good
oil is good
all coils are firing
grounds are good
no engine noises other than the occasional sounds that accompany an intermittent rough idle
how does one go about measuring fuel pressure easily?

thanks for the thoughts. I’ll check resistance and voltage at the injectors and temp sensor outputs

 

How did you check the battery, and how did you check the grounds? If you check the battery with a multimeter and it's measuring over 12 volts that does not mean that it's providing enough amperes.

To check the fuel pressure, you have to have a fuel pressure gauge and the adapters to tie into the fuel hose at the line.

 

how about a bad MAP sensor?

 

Circling back: problem seems to be resolved after replacing the fuel injectors . thanks to all who gave suggestions.