Problem starter!

hi my 3.9 v8 is having trouble starting! fuel pump is strong, spark is good earth straps are good its making all the right noises but only fire's when it has throttle where as before it was not needed.
i am at dead end can anyone offer some advice on this?

if its injection could be crank sensor, if carbs then are they blocked, idle control?

maybe tell us if it will run at idle once started or does it still need throttle? is it same warm and cold?

It would be useful if we knew what motor we are talking about, gav suggests crank sensor but you might have an older 3.9 that doesn't have a crank sensor.

Have you moved the dizzy at all? Anyway search all of LZ for V8 starting/running type problems and the answer is out there, you might have to do a lot of reading but you will learn so much it will make your head spin.