so ive been having this problem for a while now and ive tried everything i could possible think of. I have a 94 3.4l automatic and its having a rough idle and a check engine light thats going off and on.

the codes came up as the EGR, IAC, and TPS so i replaced them. That lowered the idle from about 1800rpms to 1500 rpms in nuetral/park and to about 1000 rpms when in drive. so my next though was tune up/vaccum leak. so replaced the wires, ignition, and plugs with performance parts and triple checked everything. she ran way smoother but still the idle and check engine light came on and off. when doing a vaccum check i discovered that there was a great amount of suction coming from the area were you put oil in and also that when i choked the Throttle boddy the engine was still running!!! i choked the PCV air in tube and the idle dropped to 800 in park. I must add that the A/C is not blowing cold and oil pressure gage will drop to 0 some times when not on the gas. any ideas of whats wrong would be amazing thanks

PCV valve is working and my next guess is bad CAT? theres some rattling coming from under but an exhaust shop said a bad cat wouldnt make the check engine light come on on my model. He may be right about that? but if the cat wont come up mabya bad cats causing the EGR to come up? Im all out of ideas and the cars idle is horrible and just sounds horrible

help plzzz

 

Did you reset the computer clearing codes???

 

Sounds like its getting too much air through the PVC system. Do you have the vacuum connected to the correct source? You indicate that the PVC valve is working, but how did you determine that. The valve acts in two ways, and one of them is to limit vacuum at low engine rpm/high intake manifold vacuum conditions. Did you check the PCV vacuum line for cracks?

With regard to the codes, what ones are coming back? What are the specific numerical codes?

When you had the TPS code, did you check the throttle blades to make sure they are closing all the way?

 

well i unplugged the battery for 5 min and tried ressetting em that way.

yeah thats what i was thinking is to much air is going through the pcv i checked the valve by shaking it lol sounds newb but it sounds like its working
Ill replace it though its 5 bucks and update.

yeah checked the vaccum line no cracks

ill try and get the codes again with my dads friends OBD1 and post em

and how would i check the throttle blades

thankyou guys alot for the help

 

Take the air intake ducting and MAF sensor off and look at the throttle blade, to make sure that when you release the accel pedal, the blade fully closes. There's just one "blade".... I said "blades" out of force of habit dealing with the LT1 and its twin blades.

 

just updating i checked the throttle blade its fine

i noticed something really strange though when inspecting my car after driving it

It was making gulping sound after it was off sounds like someone downing a waterbottle was coming from a larger black hose i felt it and there was liquid flowing through and was making that sound any thoughts could that be my problem thanks

 

could it be an intake manifold leak thats causing my idleing problem and the gulping noise? the car does leak oil when parked