Backfiring increasing with cold temps.

I'm sure some of you remember me complaining about my Jeep backfiring after putting a "new to me" motor in. Well, it's started to do it more now that we've seen some 30 degree days. If I drive it from a completely "cold start" in the morning I can hardly get any power at all especially with the colder weather, but once it gets warmed up the backfiring quits. The only other time I hear it is at like 65< on the freeway. Is there any sensor that can be affected by outside temp and telling the computer wrong info.? It doesn't actually sound like it's missing when I just let it idle in the morning, it's just when I start stepping on it. BTW It's a 1990 Renix 4.0, all sensors new within the last 2 months except the 02. The 02 sensor is going on 2 years since a change. Just changed plugs, wires, and cap/rotor. Can anyone point me in the right direction?
Thanks guys,
Collin

Check the EGR, both on the manifold (make sure the little rod goes up and down) as well as the vacuum and the solinoid that moves it. EGR failure is classic renix, with symptoms like slight miss and stumble on accelaration, and at speed, and once it warms up it goes away. Heres a renix diagnoses site that might help as well. good luck
http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

XJING said:

Check the EGR, both on the manifold (make sure the little rod goes up and down) as well as the vacuum and the solinoid that moves it. EGR failure is classic renix, with symptoms like slight miss and stumble on accelaration, and at speed, and once it warms up it goes away. Heres a renix diagnoses site that might help as well. good luck
http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm

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Ahh sorry forgot to add, its a 91 Intake so no EGR to worry about, it's gone. Any other ideas?

If you did a 91 intake than you put the renix TPS on the 91 TB? This is what I would check next. It was hard to tell what motor you are talking about reading your post BTW.

Check you distributor alignment. I know, you did it right, just like I did. That's why I say check it again. Mine was off a tooth and experienced exact same problems on a new engine. Fixing made it all good.

XJING said:

If you did a 91 intake than you put the renix TPS on the 91 TB? This is what I would check next. It was hard to tell what motor you are talking about reading your post BTW.

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Yeah man, you were actually the one that suggested checking the idle circuit when I had the low idle. I did everything right, I'm using all the right sensors, so I'm pretty confident unless it's the 02, its not a sensor.

Nevada City Sparky said:

Check you distributor alignment. I know, you did it right, just like I did. That's why I say check it again. Mine was off a tooth and experienced exact same problems on a new engine. Fixing made it all good.

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I will definitely check that. Now do you mean just move it around in the groove it's in, or pull it out and move it over a tooth?

check the ignition system thoroughly. I recently found a wire that the insulation was damaged, and the colder temps made it shrink. Shrnking inslation let the spark jump and I got a cold miss on cyl #3. Replaced the wire, all was well.

check the distributor for proper aloinment. there should be a few posts to tell you the right procedure.