once warmed up car dies.

[JLBMX5]

I have a 1993 miata with a 1994 1.8 motor swap. I am using the 1.6 throttle body and air intake tubing. Been swapped for about a year now. Here is my new issue
My miata started acting up today. After driving awhile I stopped at a light and car died. Idle really low. I had ac off. Soon as I turned ac on it would idle at 1000 rpm but soon as I turned it off it would drop as low as 200 and sometimes die. Anyone have a clue. I read some on iac valve but no clue on how to clean .

[Agent☣Orange]

Seems like your IAC is working fine since it kicks up the idle when the AC is on, maybe too much. I'd do the preliminaries first and check for vacuum leaks first and replace any old, brittle lines.

[JLBMX5]

After thinking about it a couple of days ago I had to pick my daughter up from practice and as I was sitting in parking lot my idle went from 900 up to 2000 back down to 900 then jumped up to about 1500. Was kinda haywire. Ac was on but not blowing all that much of cold air. It never does when sitting still. I just shut the car off and waited till my daughter came out before starting it back up. But when I did start it back up I had ac on so I did not notice that idle drop. Its not running rough and I cant seem to find a vacuum leak at all.

[Agent☣Orange]

Starting to sound electrical now, like a ground problem IMO. I'll let the NA experts chime in though.

[JLBMX5]

Might be a vacume leak im not 100% sure till I do some driving. Today when I got off work and I drove home I popped the hood to look at things and the little nipple on the intake manifold had the cap going bad. I just replaced it last month with a two pack that I purchased from advanced auto. So today I replaced it again but wont be able to tell if that was the problem untill I put about 30 miles on the car in one sitting. I only drive 5 miles to work. Another question I have is that cap. Like I said I bought from advanced auto and I dont want to be replacing these every month so anyone know a better material that will last awhile. Or atleast tell me why it looks cracked and dryrotted looking in little over a month.

[kung fu jesus]

Replace your vacuum tubing. $15

[JLBMX5]

Replace your vacuum tubing. $15
Its not the tubing. Its only the little nipple that is giving me problems. I replaced it a month ago and it looked as if its been on the car for 20 years so I put another one on it but I would like a refrence on maybe a better supplier than advanced auto for a quality part that will not fall apart in a month.

[Agent☣Orange]

That's a good question actually. I've bought some from Ace Hardware before and they seem to deteriorate pretty fast but the OEM ones I've bought from the dealer or Napa seem to last as intended. All rubber will deteriorate in a car but yeah, we should get more than a month of use.

[JLBMX5]

Only time im out near a dealer is the weekends so its hard to buy parts from local dealer when they are closed. I will have to check out napa and see what they sell. All I know is the crap you buy from advanved on their help rack is crap and im not buying any more of them.

[JLBMX5]

I found a throttlebody on ebay that has been cleaned and has all the sensors attached. Comes with warranty. 89.99. Free shipping. I figured I would give it a shot. Mine has 214,000 miles on it and has never been cleaned so I will install and see if it helps my idle issue. Also I have a hesitation if I give car hard throttle in any gear other than first and am inbetween 4,000 and 5,000 rpm. It doesent happen all the time but I notice it when it does.