@George_Purpura

If unit has a k21/k25 LPG ecm controlled injector engine

e35 = fuel injector disconnection (open circuit malfunction) Check main injector coil for open (Resistance I think around 1ohm but cant remember), check injector power fuse located inline on injector harness, if good then verify wiring to the ecm. Dont forget to check connector pins for spreading terminals.

e36 = fuel pressure sensor malfunction
Most likely caused by bad wiring directly next to connector or broken wiring in the connector. Give a good tug on each wiring going to your fuel pressure sensor located on the throttle/mixer assembly. Somtimes caused by a bad sensor but not usually. (0psi fuel pressure will not set a code in ecm due to it thinking it ran out of fuel). Verify all wiring to ecm is good. I cant remember exactly what pins but the fuel pressure connector should have an ecm sensor ground on one pin, 5v reference on one and sensor signal on another.

@Dave T
I know its an old post, just thought I would mention you should have someone clean the throttle body and perform an idle relearn in the ecm. You should also spend a couple min and check the main injector O ring for splitting as well as the assistant injector, as this could be an over fueling issue at an idle