My 95 z Starts right off and runs fine 75% of the time. The other 25% of the time either it is a hard start and you have to hold WOT to start it or, more often, it starts fine but starts to stumble at idle or while driving slowly out of my neighborhood. If I feather the throttle when it starts to stumble sometimes I can keep it from dieing but alot of the time it dies. If it dies you have to hold WOT and crank for a while to get it to start again. I have noticed that if you can get it out on the street and open the throttle it seams fix it. It hasn't been throwing any codes. I am thinking it is leaky injectors but the problems are random. How can I test the injectors since the issue is usually while I am driving?

Some back ground: I only drive the car about once a week. New battery, new opti 2 years ago, I was told a new fuel pump right before I bought it 2.5 years ago.

 

Test the fuel pressure first and see how thats doing. Then from the results it might lead to the problem. See how it does with the key on but not started, with the engine running, with the vacuum line on the fuel pressure regulator disconnected and while driving, if possible.

 

Wow it has been a year since I posted this. I haven't got to drive the car a whole lot in the last year but when I have I haven't had this problem. Last week I drove it to work and back, about a 25 mile round trip. I didn't have any problems until I was about 5 miles from home. I was on the interstate and it started to cut out under excelleration. After I got off the interstate it dies and I had to hold the throttle open and crank for a few seconds to get it to start.
I bought a fuel pressure guage and watched it while I drove. It is at about 30 psi when I turn the key on. While driving it stays 38-40 until I open it up then it jumps to 46ish. While I was doing this it did studder and die with no noticable change in fuel pressure. I had data master running but I guess I wasn't recording. It didn't kick the SES light today but has in the past when it does this. The stored code is 15 which shows as a low engine temp or malfunction. I have replaced the temp sending unit in the waterpump and repared the wire that looked a little crispy. Does anyone have any suggestions?