Hey guys, I have an issue with a rough idle on my 1994 3.0 Ranger I've been putting off for a while.

Description:
On a cold start in the morning, my truck cranks strong then idles VERY rough until it either stalls a couple of seconds later or shakes the entire truck until I warm it up. I am able to get it warmed up by giving it some gas, then it runs alright with a semi-rough idle.
On a semi-warm start after a 5-minute drive, the idle gets progressively worse for about 20-60 seconds then starts to even out to a semi-rough idle.
Once up to operating temperature, the rough idle is hardly noticeable. However, several times when idling for an extended period of time (usually while waiting in line), my truck suddenly idles badly then stalls out, even at operating temperature. This has only happened 3 or 4 times in 2 months and it always starts right back up with a little help from the accelerator.
When I let my truck idle rough for 5-10 minutes I start to smell gas, this is something I never noticed before the problem started.

Troubleshooting:
My first thought was a vacuum leak, so I started spraying carb cleaner at every hose. I went through three cans looking for hours and actually ended up fixing a few leaks, but it didn't fix the problem.
My next idea was the Idle Air Control Valve (IAC), so I took it off and found that it was pretty dirty. I cleaned the hell out of it with carb cleaner and put it back on, then tested that the voltage was correct. Started it up but my rough idle was still there.

I decided to hook up the OBD1 code reader yesterday and came up with a few codes.
KOEO Test:
332 - "Insufficient EGR flow / EGR did not open/respond intermittently" (from continuous memory)
KOER Test:
412 - "Cannot control RPM during KOER high RPM check"
536 - "Brake on/off circuit did not activate"
538 - "Insufficient RPM change during KOER dynamic response test "

I'm thinking about replacing my IAC and EGR valves and seeing if that fixes my problem but I thought it wouldn't hurt to ask around here first.
All advice and suggestions are appreciated, thanks.

 

MAF?

 

An EGR not functioning and stuck open will cause a lot of idling problems. It will behave like a massive vacuum leak. An EGR stuck closed or its passages clogged can cause pinging. The MAF sensor as mentioned can be the culprit. You will have to do some testing. You said you smelled gas so take a look at the fuel pressure regulator. Pull the vacuum line and look for raw gas. Have you pulled the spark plugs to inspect? BTW.. when you press the accelerator, you essentially are giving it more air. With fuel injection the pedal is an "air" pedal instead of a "gas" pedal. The TPS sensor on the throttle signals the computer as to how much you are pressing the pedal so it knows how much fuel to deliver. If you are already getting too much gas the computer is unaware of... that's a problem.

 

I took off my EGR valve (resulting in a 4-hour headache because one of the mounting bolts sheared off and I had to drill and tap a new bolt hole), cleaned it out with carb cleaner, and tested the valve with a hand vacuum pump. The EGR seems to be in good shape. I tested the throttle position sensor with an electrometer, it read 5V. When I pull the MAF the idle slows down and gets rougher so I think it's functioning. I'm gonna look through my vacuum line and fuel pressure regulator next. Any other suggestions are appreciated, thanks.

 

It was my ignition control module I replaced last year.
They shouldn't go out that often, the reason mine went out is because I had an indirect short between my Alternators B+ wire and my starter solenoid causing undue stress on my recharging and ignition system.
Thanks guys.