All those are good ideas, but do the seafoam last after you see impact of others. Also inspect for vac leaks, cracked vac hoses, cracks in air hose from MAF to engine. Also want to clean the PCV system, has a vac line on both valve covers, one to plenum, one to throttle body. One to plenum has an oil separator, pull hose out, remove separator with needle nose pliers, sovent clean and replace. Looks like a series of corkscrew baffles.

 

So I cleaned my IAC and now it definitely improved the idle but I still have a rough start. I just went out to check it and hooked up my fuel pressure gauge. When I turn the key the psi shoots to 40. But if I don't start the car, it slowly falls to about 20.

When I actually start the car the fuel pressure stays steady at 30, which from what I've been reading is still low. And when I turn the engine off it slowly falls until there is no pressure which takes about 4 minutes.

Should it be doing that? I have replaced the fuel filter and pump, plugs and wires. I have no vacuum leaks. New battery. It does have Regular gas in it though. Could that be my problem? WIth the psi falling the way it does could this mean my injectors are clogged? Should I replace the multifunction relay?

 

Fuel pressure is OK, it drops off if you don't actually start the car in a few seconds.

Put in premium gas, then you'll have a tank of sorta premium, next fillup, premium.

Fuel pressue does not remain trapped in a high state.

 

Do you think that's really the issue, bad gas?

 

The O2's will not cause the problems you are having.
Bad gas might.
Add a can of Seafoam to the gas tank, then go top it off with premium and see what happens.

 

What else would cause the rough starting and stalling?

 

Rough start and stalling...low fuel PSI, weak spark, bad/dirty IACV, clogged air filter, dirty MAF, bad gas, cheap gas, to thick motor oil can cause hard starts and stalling at idle when cold, ignition timing to far off, sticky valves, low compression, bad/wet ECU...

 

Fuel pressure is steady at 30 when running. I just cleaned my IAC, MAF and throttle body and air filter. It has 10W 40 Mobil One Oil. The ECU seems fine.

I am going to add a can of sea foam to the tank and top it off with supreme gas and see what happens.

 

Added a can of seafoam and filled up with premium. Went for a 20 mile drive and all was going well. Stopped the car, had a rough start again and now that it was up to regualr running temp it wanted to stall at every stop. So it seems that when it heats up the problem gets worse. I'm wondering about the IAC. With the car running I unplugged the IAC and there was no change, I even put it in gear and backed it up and pulled it forward. It was running rough but didn't die.

I just cleaned it, but possible it's bad and needs to be replaced?

 

Yes it is possible that your IACV is bad.