Pontiac Repair: 1994 Trans Am electircal or engine problem?, new distributor cap, water pumps

Question
My husband owns a 1994 Trans Am with 94,000 kms on it.  Last year we had problems with the car.  We would be driving down the road, and all of a sudden the car would start to jerk, then back fire and the engine light would come on.  Once the engine light comes on..the car runs like a dream.  It has all it's pep back and you can tell it wants to go, but the engine light is on.

So we took it into GM, and they changed the spark plugs, and told us the Distributor needed a new cap.  So we replaced that..cost us $1600.00 to do so.  Picked up the car, drove home (which is 3.5 hours away) and had no problems.  Winter came, and we stored it away, in a heated shop as we have from day one (car is driven only about 5 months of the year).

We are now having the same problems.  The car jerks down the road, backfires and the engine light comes on.  Then it runs good again.  Took it back to GM (the car is still there as I write this) and they changed the sparks plugs again.  That wasn't the problem.  Now they are saying we may need a new distributor to go along with the new distributor cap we had replaced last year.

Also..sometimes when you give it gas quick..it kinda stalls..almost like it is getting too much fuel?

GM tells us that they have never had this problem before.  They called their tech center, and they say they've never heard of this.  There has to be someone out there that has had the same problems.  

The car is a 6speed transmission.

Any help or suggestions would be awesome. Thank you.

Answer
Hi Becky:

These cars were noted for distributor issues. It has what was called an opti spark system. If any mositure gets into the distributor they are JUNK then. just from sitting and condensation can get into the distributor and cause all kinds of issues. They also were noted for water pumps leaking and dripping coolant onto and into the the distributor on these cars. These were also notted for corrosion to build up on the coil wire and coil. that will case issue as well. I don't remeber which year they started with a vent system on those distributors they had a vacuum line that plugged into the air inlet hose between the air filter and the engine and then down to the distributor It had a blue vacuum tap on the air inlet hose make sure that is connected if this is the year it started Like I said I can't remeber when they started with that. The made a BIG difference on these systems less distributor failures on the newer version of the system... I'm not sure but you may be able to retrofit the new system onto the older systems... I never looked into it but it may be worth looking into... Good luck :}