I have a Chevy G20 Van 1989. The problems seems to be: Sounds like it is burping or coughing air up and out the carburetor, the Idle sometimes slows and stalls. Runs fine at normal speeds and coughing sometimes is not present. But when slow to Idle that is when the coughing sound begin the Idle slow the vehicle may stall The Map sensor and throttle position sensor has been replace.
I would look at basics first. Check fuel pressure, compression and spark.
When was the last time you had plugs, wires, cap, rotor and filters changed?
May, 8, 2013 AT 5:29 PM
The Plugs and wires, cap and rotor and filter may have been changed about a year ago I think. Key point when I changed the map sensor and TP sensor It ran fine and the problem was gone for a day but re-emerged.
May, 8, 2013 AT 5:47 PM
Neither one has a real effect on your issue. You may have disturbed somethign replacing these sensors but if you put back the old ones, it will be the same