Hello, my name is John and I have been reading about the common problems with these Chevy express vans with the spider fuel injection sytems.
I recently bought a Chevy express 3500 with a 5.7
I purchased used for work purposes. I gave the van a complete tune up and suspension items and rode for about 20,000 miles and now van is not running well. The check engine light flashes at idle and I have replaced all related sensors the fuel spider injection twice and checked compression all reads at 120-115 psi and replaced the distributor assembly. All ending in the same result.. flashing check engine light at idle. If anyone has run into this issue please post on this subject. Thanks for reading

 

I had similiar problems. I changed the MAF Sensor and it ran like new afterwards. Did you check the codes?

 

I have the dreaded po 300 and replaced the map,MAF,,cam,crank sensors, replaced the spark plugs. I also checked for leaks on the intake gaskets.
I'm really stumped on this one. Only thing I can think of is that a possibility of a clogged up cat or burnt valve on exhaust.van starts right up but light flashes and has a noticeable miss in it.

 

You didn't mention the year. Do you have a distributor? Those can be the source of misfires.

 

The van is a 2001 with a 5.7 and I replaced the distributor with a new aluminum one as I heard bad reviews on the stock units as they are made out of plastic. Still continues to do the same as when I pulled it in my driveway for repair. Flashing check engine light with the accommodating po 300 code.
Checked the computer for any evidence of water damage and none existed. Has anyone else ran into this mystery?