Friend has a 88 L05 and we just adjusted the timing on it because he recently got his distributor rebuilt, we went for a test drive and I told him to mash it (he normally doesn't so this problem might have been around a while) it started surging. I then asked him if he remembered to hook up the EST wire which he didn't so we pulled over and hooked it up without restarting (does it make a difference?) Tried it again and same surging at WOT. Anyone have a cure?

 

The EST connector makes a difference. You need to pull the ECM B fuse to reset the code in the ECM. Sometimes simply cycling the key will make it go off as well.

Fuel Filter?

 

Mine did the same thing. Was a TPI though ended up being the EGR valve.

 

You need to shut down before reconnecting the EST in order for the ECM to reset to normal operation.

 

We recently replaced the EGR about a week ago actually.

I'll have him try it tomorrow since it will hopefully be reset being shut off.

Fuel filter is fresh, though we're going to disconnect the lines this weekend, blow them out with compressed air and then replace the filter again.