Well I installed new Plugs (NGK BPR5EY) V Groove and love them much better power.
I installed these along with Karlyn / STI Wires (Very nice quality) no more misfires.

I also Seafoamed the Intake and Gas....
Fuel filter and fuel pump relay are new.
IAC Stepper motor has been cleaned and lubricated.

Truck is still idling rough when warm at red lights in Drive...
RPM dips from 700 to 500 and back

Any idea?
Only code is 19 for the Mass air or TPS Sensor....

Where do I go with this one now Mike?
Thanks guys it is running much better now

 

Vaccum leak, possible carbon build up, have you clean out the throttle body? What about the cap and rotor, are they new and factory?

 

be REAL careful pulling the rotor "off" -- the distributor has a 2 part shaft and if your rotor is stuck more than the plastic "hat" that connects the 2 shafts then it will pull the distributor apart - and springs go flying. When this happened on my 93 SWB 3.9L the kit containing the little plastic button was more than $100 (I think it came from DAP inc.) and a few days shipping. That plastic part was far more than gold or platinum in price (seems to be to common for landrovers). I did rebuild the whole distributor at that time AND found my vacuum advance had a hole in the diaphragm ( another $100 or so and a few days wait) -- it would not hold vacuum. It must have been that way for a long time -- it really helped the engine run better.

Advice -- after you have replaced everything inside the distributor spray it with WIRE DRYER ($2 at many parts stores) and the RTV BLUE SILICON the cap to the distributor and each of the wires to the cap. RTV the amplifier wire connection. Also RTV the wires/connections at the coil. Of all the electrical fixes to ignition on the rover, that one helped the most to smooth out idle, ensure quicker starts, and generally run better. You could also RTV blue the wires to the plugs, but simple dielectric grease seems to do the job best there. Keep a flat screwdriver and $2 work gloves in the rover in the event you need to get the cap off 4 wheeling. It might look ugly, but it does 10 times the job of silicone or dielectric grease.

the underside of one vacuum hose was cracked and drew water into the block about a year ago -- the result was it steamed the water and fogged it into the distributor cap (even though it was sealed). We run a mantek snorkel and have every other orfice possible sealed up due to the more than occasional 4' wash. It took a while to figure out where the water came from -- it was the part of the "T" hose that goes toward the battery in our case. Those hoses were replaced about 4 years earlier but possibly we got old stock(??) and it oxidized quickly.

There is something else called a stepper motor that might affect idle. Mine hasn't gone yet on either rover so I can't comment there....

 

another thing to try is MAF (mass flow air sensor) cleaner. Disconnect and remove it to clean the backside as well and keep the grime from going into the intake.

I was running a K&N (oiled) air filter and the oil is pulled downstream into the MAF and intake. Then the oil attracts carbon/junk buildup. Do this especially a few hundred miles after re-oiling the filter. Most folks over-oil the filter, making the problem worse.

It was like a tune-up cleaning mine.