off-idle, coast rough

[NAJ]

We use an air pressure operated system with a concentrated GM cleaner(works much better than the Mopar stuff which is made by Wynns.)You add 2 ounces of cleaner and the rest gasoline.
Disable the vehicles fuel system,disconnect and plug the FPR vacuum line, connect the cleaner canister to the fuel rail, connect shop air, set the regulator to under regulated pressure, enough to keep the car running and start the car, the vehicle runs on the cleaner only, let it run until empty and reinstall all disconnected components.
It will also clean carbon from the combustion chamber and piston tops.
Most repair facilities offer injector cleaning service.
My Son bought his own kit and chemicals.
If you have access to an injector tester(will pulse each injector at a pre-determined rate) you can run injector balance.With a fuel gauge connected toggle the key(engine off) until you reach max regulated pressure, push the button on the injector tester and the injector will pulse, record the pressure drop, repeat for all cylinders(being sure you start with the same fuel pressure for each cylinder). all cylinders should drop equally, if one or two have a lower pressure drop, clean the injectors and retest, if still low, replace the injector.
I have an OTC injector tester, I have had it since 1988, it has 3 different pulse settings,
they sell for about $100.00.
The injectors have to be cleaned from the inside, it is ironic that even with all the detergents added to gasoline to prevent this it is the gas itself and injector design that is the culprit, heat, carbon, parafin, and a pintle.
You never see a TBI injector get dirty, they do fail but do not clog because they are not exposed to engine heat and use a ball and spring instead of a pintle.
Gm developed the "Multech" injector in the late 80's that was a high pressure ball and spring MPFI injector but due to engine heat and carboned based fuels it did not fair much better.

[mmtphoto]

replaced the stock ig coil with a msd blaster 2, seems to have fixed the problem-drove it over 100 miles yesterday, and it pulls hard to 13 lbs. and was smooth as silk. I am going to get the injectors checked and cleaned anyway, ordered new o-rings-I am getting it to where it was when new now, looks and runs great.