Well I have this starts goes dead issue unless I quickly push the acelerator pedal. Once it races to ~3K rpm it wants to die unless I push the pedal in a couple times, then it seems to be ok. No sign of vacuum hose issue, MAF sensor connector tight and air hose to TB looks ok. ?????????????

90 Vert MTX

 

fuel pump?

 

Dont thin its the fuel pump. Replaced it a couple months ago w/filter in tank and inline filter. It was Mazda OEM.

 

What mods to the engine? Have you removed the AWS--the emission stuff? More info might help.

 

100% stock. I think I found the problem. The double throttle diaphgram on the front of the TB will not hold a vacuum when I try to test it using a vacuum pump. So I think the diaphragm is dead and the TB gates that open want to slam shut upon start up. Not 100% sure because if I hit the gas a few times it will not die.