This all started with out warning. She was running great the night before and then...terrible. You have to stay on the gas untill it goes in to closed loop and then there's a bad hesitation every time you give it gas. Tried adjusting the IAC with no luck. I'm getting about 17lbs vacuum but it fluctuates about a pound. If I recall, I used to have about 20 lbs. Any ideas??

 

Sarge,

I'm a little confused (doesn't take much) but your signature says "LG4" but you mentioned an IAC, so that points to an injection system. If it isn't an EFI system, disregard those parts.

In your spare time, start looking for a vacuum leak. In addition to all the usual suspects like vacuum hoses and gasket surfaces, don't overlook the brake booster, PCV system, the EGR system, and the vacuum lines and MAT sensor under the plenum (EFI).

Of course, this is all assuming that the ignition system is working properly and the injectors (EFI) are firing, but even a dead plug or injector won't necessarily cause a drop in vacuum, only idle quality. 17" is a little low for a stock cam at normal idle RPM, but not completely out of the realm of possibility. If you had 20" Hg before, that should be a good guide.

Keep us posted.

 

I was thinking the large adjustment in the top of the carb was an IAC. I'm going to dig around more today for a vacuum leak. What's the best way to check if there's a leak in the brake booster??

 

Checked the brake boost line and it's fine. Any other ideas?? The vacuum reading should be steady shouldn't it?