64elko

hello guru's i have 5000 miles on my new 350.. it has a rough idle on start up and after warming up... every part is new... checked for vacuum leeks none. checked injectors,all good. checked fpr good psi ,checked fuel pump 45 psi... voltage is .45, .IAC good tps good. every part is new. stumped here guys.....

southbay08

did you check resistance on the injectors while hot and cold?

89RsPower!

Are you positive your base timing is right? Are you setting it with the est bypass connector unplugged? Are you sure that all of your plugs are firing? If you're sure of all of those things and that your tps and iac are adjusted/working properly (also prob not your issue if you just put it all togather and most likely cleaned everything up first, but do you know for a fact that the iac passages are clean and clear? Carbon build up in the iac passages can cause the plunger to stick, prevent it from seating properly, or simply cut off enough air flow that it's impossible for the valve to work as designed. The only way to know for sure is to take it apart and look. A multimeter can only verify that the electrical component of the iac is good. If you already know it's clean, clear, and working properly nevermind, if not buy some tb/carb cleaner, a new throttle body gasket and a small stiff brush and with the tb off the car and the iac out clean out the passages as good as you can and also dissassembly, clean, lube and reassemble the valve (IIRC there is a how-to on here that will take u step by step if you are unsure)
Now that I just probably typed a novel for something probably unnessicary if you are certain of everything mentioned being good next place to look is the injectors. As southbay asked have you ohm'd the injector coils to make sure they are all within spec? If so have you checked for injector pulse at them all with the engine running? If you get that far and still havn't found an issue I'd suggest physically pulling the fuel rail and checking the injectors for proper/any flow. Best way I've found is 8 baby food jars, place them under each injector and crank the engine as if you were trying to start it while watching. Note the spray pattern and most importantly look in the jars to verify they are all spraying.

Edit: Is this a MAF or MAP setup? Have u checked for codes? How are you monitoring sensor outputs when its running? Is this something that just started to occur or has it been like this since your swap? Assuming it was a 305 to 350 swap did you replace the old knock sensor for the proper ks for a 350? Does it always run this way or only in closed loop? If it is a MAF setup have you tried running it w/o the maf sensor connected? If it is a maf sys and you havnt tried give it a shot to rule it out, a bad or malfunctioning maf sensor on a tpi car can cause an engine to run like crap without setting a code, if left unplugged the ecm will operate on preset values and allow it to run normal. Also it's the quickest way I know of to check it