Misfire issue/question

[mousemonster1232]

I am having an issue with misfires on a 1999 GP GTP.

The parameters in which it happens (intermittent):

-approx. 40-50 mph
-cruising

When it occurs:

-when you gun it

Basically if you are crusing at about 40-50mph, and then you gun it, it will misfire continuously for about 6-7 seconds if it is held down, but if you let go, give it a sec, and step back on it, it seems alright, but kind of laggy.

I first thought the tranny wasn't downshifting, but now that it has occured more, I notice it definitely is misfires.


I changed spark plugs just recently (within past month n half), so it should not be them. It isn't a highly modded car (yet) so I don't think it is a mod I have done either!


Any suggestions will help!


Thanks

 

[SlowRR]

When you did your plugs did you change the wires? If not that's most likely going to solve the problem.

 

[mousemonster1232]

Nope, I have not changed the wires, I was going to do that today, but idiots wrote my paycheck for two days after today, so I need to wait another two days.

 

[cliffdawg]

check vacuum lines same thing to me. check for cracks

 

[mousemonster1232]

check vacuum lines same thing to me. check for cracks

Will do that as well. Just the ones on the top of the engine with the T things in it (MAF, S/C thing, and one other connection)? This car has already had those crack once before (not when I owned it though).