98 GMC electrical on 5.7

[98GMCpickup]

Hello, I just replaced my intake manifold gaskets on 98 GMC 5.7 liter. Got it to start instantly on turning the key. Problem is that it does not want to go faster than a low idle. About 4000 rpm. Can get it to rev up a little bit it I really pump the gas pedal.

Also, there seems to be an electrical problem. The interior lights go on and off and the guages go crazy while running. Sometimes it starts only after pumping the gas pedal. Not able to drive it at all.
Thanks for any help. Cam

[98GMCpickup]

I just tried again and there is a clicking sound coming from the throttle body with the ignition on. It is non stop and quite rapid.m

[jdl]

4,000 rpms is not low idle. Do you think the clicking noise might be an injector? Any applicable trouble codes?

[98GMCpickup]

Thanks for the reply. I do not have a reader. 4000 may not be very low but it will only run for a few seconds without me pumping the gas pedal.

[jdl]

Some of the national brand autostores used to check codes for free. Obd2 code readers don't cost much.

[98GMCpickup]

I can not drive it so I will have to buy one.