i have the same problem I'm able to get up to 70 with no problem, but as soon as i hit a red light or slow traffic the truck starts shaking and sputtering. It has yet to actually stall out on me, but it crawls for 10 to 15 seconds. Ive tried replacing the vacuum hose, temp sensor, fuel cleaner, coil, Please keep me informed thanks.

 

The original problem was poor running after a hot start. There are actually 5 temp sensors on your 97. Engine coolant (two of them... one sends signal to ecm and the other to gague), Intake air temp (part of MAF) which retards the timing when it senses temps above 130*F, Condensor fan switch which is just a reactive element of the system not something that effects tune and finally the sensor no one mentioned.....

Fuel Temp Sensor. This sensor is the first sensor the ECM recognizes at startup. It tells the engine if it needs to richen the mixture (cold start) OR if the ecm should move on to the next most relevant sensors for proper open loop running since the engine is already warm... engine coolant (two pin sensor), MAF and the most important sensors of all the O2's.

With the ingnition OFF, Pull the plug off the sensor and test its resistance across the two pins. You should see these values:

1,100 ohms @ 104*F
300 ohms @ 185*F

This sensor is a thermistor and as the sensor heats up the resistance values (Ohm's) will go down.

On a side note, have you replaced your oxygen sensors ever ? those do more to alter the air:fuel mix than anything.

As for the fuel pressure regulator.. the very simplest test requires NO gague at all... not even your trusty tire pressure gague at the schrader valve. Pull the small vacuum line off the regulator and check it for no cracks or splits. then take a longer piece of tube and put it on the regulator and suck on it. if you have air resistance you should then the diaphram is most likely still good. However, it can still cause you issues.

Fuel Pressure regulator is the only component in this particular system which does not illuminate the CEL.

One BIG probblem here though. When you removed the IACV plug the CEL should have come on. You may have a bulb out .

Pull the MAF plug too and turn the ignition on but don't try to start the car...see if that turns the CEL on.

 

Just a note I am not as adept as most of these guys and your problem doesn't sound as extreme as mine was but....my ecm was corroded through because they put it by the washer bottle. It only takes a few minutes to take it out and look at the box if it is bubbling away or the box looks really bad you can open it up and take a closer look at the inside....like I said your problem doesn't sound exactly the same as mine but it may be the beginning of the corroded ecm...they put it in a really bad spot. disconnect the battery first of course. may be completely off course but it only takes a few minutes to check.

 

Installed the fuel pump today and it didn't solve the problem.. I decided to put in the old IACV and see what happened and it started working normally, no stalling. My guess is that the new IACV is bad, I'm going to send it back and get a new one.

 

Speegles,
Did you have issues of high rev when the LR was warm?