90 Grand Am Missing at acceleration

1990 Pontiac Grand Am Quad4 ~156k miles, Auto transmission Having intermittent problem with missing(?), backfiring in engine somewhere (not out through tailpipe), has stalled when accelerating from a stop and while at a stop (idling). Seems to start missing(?) when accelerating quickly on occasion. Even when it misses, there is a point during acceleration that things seem to come together and the missing clears up and the car will run fine, until it's time to accelerate again. None of the problems are continuous or consistent. On some days I have driven to work, about 3 miles, without any problems; and I always have to stop at stop signs and traffic lights. Some days it's a wonder the car got me to work. Not sure if this is related, but I have noticed a slight loping at idle. The loping has been there for quite a while and is still present. I've read there can be many causes for loping. Actions taken so far: replaced a broken vacuum line to the fuel pressure regulator and replaced the oxygen sensor. When doing those two jobs, I disconnected the negative battery cable while working in order to reset the computer. If anyone cares to reply, I would imagine you might need more info, so just ask and I'll be glad to provide all the info I can. I'm really not in a position to replace the car, so I am hoping to find some help.

Thanks, ATL

start with ignition system, you have a coil tower with two coils inside replace that if not done already.

"ATL" wrote: > 1990 Pontiac Grand Am Quad4 ~156k miles, Auto transmission > Having intermittent problem with missing(?), backfiring in > engine > somewhere (not out through tailpipe), has stalled when > accelerating > from a stop and while at a stop (idling). Seems to start > missing(?) > when accelerating quickly on occasion. Even when it misses, > there is a > point during acceleration that things seem to come together > and the > missing clears up and the car will run fine, until it's time > to > accelerate again. None of the problems are continuous or > consistent. > On some days I have driven to work, about 3 miles, without any > problems; and I always have to stop at stop signs and traffic > lights. > Some days it's a wonder the car got me to work. Not sure if > this is > related, but I have noticed a slight loping at idle. The > loping has > been there for quite a while and is still present. I've read > there can > be many causes for loping. Actions taken so far: replaced a > broken > vacuum line to the fuel pressure regulator and replaced the > oxygen > sensor. When doing those two jobs, I disconnected the > negative battery > cable while working in order to reset the computer. If anyone > cares to > reply, I would imagine you might need more info, so just ask > and I'll > be glad to provide all the info I can. I'm really not in a > position to > replace the car, so I am hoping to find some help. > > Thanks, > ATL