1993 astro engine problem

bought this van recently and ran great until it abruptly died while waiting at a traffic light. would not start. wound up pusing it home and it sat till i had some spare time to look it over (about a month! lol). checked for fuel delivery, spark, ect. Oh, by the way, it has the tbi. was visually getting good fuel delivery and good spark. plugs appeared carbon fouled, replaced. found carbon on rotor, so replaced rotor and cap. hooked up timing light. seemed ok. don't know why but decided to move dist. got it to start, barely. but wouyld not idle. had to moved dist to where timing was waaaaay off to get it to start. assumed timimg chain and took it to chevy dealership. after talking to them, they assumed same and replaced chain set. no go. had it another week and calledd that they got it running and ready to go home. said they replaced o2 and water temp sensors. it did run.... like crap. runs rough occasionaly backfires at cruising speeds(bucks like a horse). had ignition mod tested, it's fine. can't bring up codes as engine light is inoperable. anyone have any ideas what to look for next? thanks.:banghead:

ignition modules can test good but make the vehicle run like crap--- I'd use my spare module that I use to test others to prove it out-- then buy a new one if necessary if I had your van.... otherwise you can buy a new one yourself. I would not have moved the distributor- put it back to the factory setting as marked at the base of the distributor- the computer will set the timing-- I have never seen the timing chain jump on these engines- would not have suspected that.....why did it leave the shop running like crap? they should have fixed it for you!!!

bought an actron scantool, since the dashlight doesn't work. brought up theses codes; 32 egr diagnostic sw signaling incorrect egr valve operation.

33 map sensor signal voltage too high.

45 oxygen sensor rich exhaust indication.

shop claimed to have replaced o2 sensor, could the map or egr, or both be causing the o2 code?

DTC's 32 and 33 can both cause the 45 to set. When more than one DTC appears, always troubleshoot them in the order that they appear when retrieving.