Car takes too long to warm up

Question edited for a lot more clarity.
Question moved to model category.

It is easy enough to pull a plug and check for a spark. The problem is bound to be the CDI Ignition upgrade.

https://www.google.com/search?q=Digital+6+plus+MSD+box

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The rear defro does not have power going to it with the key off. This means there is somehow a short to power to this switch, if you can remove the switch check for power at the connection. If there is power there is a short, I will send you a schematic of the circuit.

Is the security light coming on? The computer chip in the key could be going bad and that will hinder starting. Good luck!

The linkage in the steering column, there is GM used 2 types there may be a bar that passes through a solenoid or a cable... they can be disabled but it will most likely take someone that knows the columns...spend the money and have it disabled unless you have a day or 2 to try it yourself...

The car should be storing a trouble code bring the car to an Auto zone auto parts store they will run a free code check this will point you in the right direction, I don't like to speculate this results in uneccessary cost to you, if I had to guess it would be a crankshaft sensor is bad or ignition related.

if after setting for a while will it re-start if so look at fuel pressure regulator chevrolet does not recomend but these are adjustable and will fix problem find good drivability person with gm background can fix you make some calls

the spark on your engine is controled by a componet called "opti-spark" it is located behind the water bump. it acts as your distribitor and ignition coil. they are a bit time consuming to change out and are very expensive! i would suggest having your local chevrolet dealer diagnose it just to be sure due to the expense involved for this unit. i hope this helps you..good luck

ps as i recall from my chevy dealership days, i beleive it was around $1000 installed..but that was a few years ago..proice could change either way now..

Take off the cover underneath the dash. Push the rubber boot down at the very bottom (Sometimes you have to cut them a little to move them down far enough) Should be an 11mm bolt down there someplace. then disconnect everything and take off the other bolts should be 13s or 15s going straight up. then just yank it out to separate it from the rack and it should come right out.

This sounds more like a transmission issue than the rear differential. It's possible that you have a damaged or mis-adjusted shift linkage or possibly a bad shift solenoid. Transmission fluid might be low, but I'm guessing you already checked the fluid with then engine warmed up and running. When it does run, does it vibrate? This could be an indicator that you have a bad seal in your torque converter and are losing fluid from it.

no special tools fairly easy job just make sure you bleed the air out of thr cooling system properly or you will quickly damage the motor