I have cleaned the threads and surfaces of the CSI and temp sender and contacts in the connectors. Still stumbles to start. I have not removed the cold start fuel injector could it be plugged or partially plugged?

 

I have seen pictures of cold start injectors that had a crap ton of carbon on them. If you pull it, be aware that you should have some new crush washers to replace the old ones.

 

That is absolutely true if you disconnect the fuel line. At least on the 3VZE, it's even easier to remove the CSI from the plenum, leaving the fuel line attached. Then, drop the CSI in a Mason jar and have someone crank the engine. If the engine is cold enough, you want to see a very fine spray. Then force the fuel pump to run by jumpering FP to B+; you want to see nothing coming from the CSI.

Unlike the fuel line, the seal between the CSI frame and plenum is low pressure, so you can re-use the paper gasket.