91 L98 Speed density. Checked and cleaned IAC, and tps is working. So i unplugged the map sensor and the car still runs without it plugged in with the check engine light on. I plugged the sensor back up and the check engine light goes away but runs the same. So i figured the map sensor was bad. My friend let me use his map sensor off his 90 TA to see if the car would idle better. I plugged it in, the car idles horrible still. So im lost, i thought if the map sensor was good the car would die? I plug my map sensor back in and it goes on the same pattern as before. Car has tons of power though when you drive it or get on it.

Wondering if its injectors? Injector 4 gave me intermittent ohms but it quit so i thought the injectors were. Any ideas with whats up with the map sensor?

 

Check for vac leaks first and foremost. Easiest and cheapest (read: free) way to start troubleshooting.

 

Yes yes vacuum lines. Just had some issue found some rotted lines so I replace all and added sealant around top of charcoal canister to be safe. Prob solved. Oh also change the fuel filter if you haven't already

 

Only vacuum lines it runs to the map. This car is a no emission car, all the vacuum lines to egr are plugged off. Vacuum lines are fine, i found the problem drivers side back runner didn't seal right for some reason, its not a huge leak, but its enough to make the car stumble. ordering mr gaskets this time.

 

Yep, leaks around the runners will do that. Make sure you torque the runner bolts nice and good, and use RTV as well (on the lower ports only).