So as the title says i have a 99 4.0 that started giving me issues a while back. It would crank but would not fire up so i tested the fuel pressure and noticed it would drop off significantly if i shut the key off. So i replaced the fuel pump and pressure regulator and the fixed the fuel pressure. Still no start. I replaced the cps still no start. Replaced the maf, iac, iat, and tps and still same thing. I see spark from the distributor and Ive tested each component and the connection get power and the sensors read their respective voltages. I should add if i feather the throttle or steadily keep my foot on the gas it'll fire up and idle fine, but when its idling like that itll bog a little bit with throttle. If i just crank it with no gas and let it crank it'll spit white gas smelling smoke out of the throttle body out of the intake filter Any ideas?

 

White smoke out the throttle body means it's flooding. It's getting too much fuel.
Classic symptom of a bad coolant temperature sensor. The one for the computer, not for the gauge. When it fails, it tells the computer the engine is ice cold, so it dumps in way too much fuel.
Feathering the throttle helps by adding more air to compensate for the extra fuel. Check that sensor first.

 

appreciate your reply, if im not mistaken the 97 and up have one temp sensor and its on the waterpump. Are you talking about that one?

 

i believe that is the one he is talking about.

 

thanks guys i think i got it sorted out. Went to O池eilly and picked up a masterpro cts, Probably gonna return it to order a better one on rockuto now that i know that was the problem.👍👍

 

It's pretty hard to scew up the temp sensor. I'd just keep the one you have. Check the wiring to the plug as I've seen that frayed and damaged causing similar issues.